Learn HTML (Full Tutorial)

HTML is the standard markup language for creating Web pages.


What is HTML? (#1)

  • HTML stands for Hyper Text Markup Language
  • HTML is the standard markup language for creating Web pages
  • HTML describes the structure of a Web page
  • HTML consists of a series of elements
  • HTML elements tell the browser how to display the content
  • HTML elements label pieces of content such as “this is a heading”, “this is a paragraph”, “this is a link”, etc.

A Simple HTML Document

Example:

<!DOCTYPE html>
<html>
<head>
<title>Page Title</title>
</head>
<body>

<h1>My First Heading</h1>
<p>My first paragraph.</p>

</body>
</html>

Explained

  • The <!DOCTYPE html> declaration defines that this document is an HTML5 document
  • The <html> element is the root element of an HTML page
  • The <head> element contains meta information about the HTML page
  • The <title> element specifies a title for the HTML page (which is shown in the browser’s title bar or in the page’s tab)
  • The <body> element defines the document’s body, and is a container for all the visible contents, such as headings, paragraphs, images, hyperlinks, tables, lists, etc.
  • The <h1> element defines a large heading
  • The <p> element defines a paragraph

What is an HTML Element?

An HTML element is defined by a start tag, some content, and an end tag:

<tagname> Content goes here… </tagname>

The HTML element is everything from the start tag to the end tag:

<h1>My First Heading</h1>

<p>My first paragraph.</p>
Start tag Element content End tag
<h1> My First Heading </h1>
<p> My first paragraph. </p>
<br> none </br>

Note: Some HTML elements have no content (like the <br> element). These elements are called empty elements. Empty elements do not have an end tag!


Web Browsers

The purpose of a web browser (Chrome, Edge, Firefox, Safari) is to read HTML documents and display them correctly.

A browser does not display the HTML tags, but uses them to determine how to display the document:

View in Browser


HTML Page Structure

Below is a visualization of an HTML page structure:

<html>

<head>

<title>Page title</title>

</head>


<body>

<h1>This is a heading</h1>
<p>This is a paragraph.</p>
<p>This is another paragraph.</p>

</body>

</html>

Note: The content inside the <body> section (the white area above) will be displayed in a browser. The content inside the <title> element will be shown in the browser’s title bar or in the page’s tab.


Learn HTML Using Notepad or TextEdit

Web pages can be created and modified by using professional HTML editors.

However, for learning HTML we recommend a simple text editor like Notepad (PC) or TextEdit (Mac).

We believe in that using a simple text editor is a good way to learn HTML.

Follow the steps below to create your first web page with Notepad or TextEdit.


Step 1: Open Notepad (PC)

Windows 8 or later:

Open the Start Screen (the window symbol at the bottom left on your screen). Type Notepad.

Windows 7 or earlier:

Open Start > Programs > Accessories > Notepad


Step 1: Open TextEdit (Mac)

Open Finder > Applications > TextEdit

Also change some preferences to get the application to save files correctly. In Preferences > Format > choose “Plain Text”

Then under “Open and Save”, check the box that says “Display HTML files as HTML code instead of formatted text”.

Then open a new document to place the code.


Step 2: Write Some HTML

Write or copy the following HTML code into Notepad:

<!DOCTYPE html>
<html>
<body>

<h1>My First Heading</h1>

<p>My first paragraph.</p>

</body>
</html>

Notepad


Step 3: Save the HTML Page

Save the file on your computer. Select File > Save as in the Notepad menu.

Name the file “index.htm” and set the encoding to UTF-8 (which is the preferred encoding for HTML files).

View in Browser

Tip: You can use either .htm or .html as file extension. There is no difference, it is up to you.


Step 4: View the HTML Page in Your Browser

Open the saved HTML file in your favorite browser (double click on the file, or right-click – and choose “Open with“).

The result will look much like this:

View in Browser


HTML Basic Examples (#2)


In this chapter we will show some basic HTML examples.

Don’t worry if we use tags you have not learned about yet.


HTML Documents

All HTML documents must start with a document type declaration: <!DOCTYPE html>.

The HTML document itself begins with <html> and ends with </html>.

The visible part of the HTML document is between <body> and </body>.

Example

<!DOCTYPE html>
<html>
<body>

<h1>My First Heading</h1>
<p>My first paragraph.</p>

</body>
</html>

The <!DOCTYPE> Declaration

The <!DOCTYPE> declaration represents the document type, and helps browsers to display web pages correctly.

It must only appear once, at the top of the page (before any HTML tags).

The <!DOCTYPE> declaration is not case sensitive.

The <!DOCTYPE> declaration for HTML5 is:

<!DOCTYPE html>

HTML Headings

HTML headings are defined with the <h1> to <h6> tags.

<h1> defines the most important heading. <h6> defines the least important heading:

Example

<h1>This is heading 1</h1>
<h2>This is heading 2</h2>
<h3>This is heading 3</h3>

HTML Paragraphs

HTML paragraphs are defined with the <p> tag:

Example

<p>This is a paragraph.</p>
<p>This is another paragraph.</p>

HTML Links

HTML links are defined with the <a> tag:

Example

<a href="https://www.apostube.com">This is a link</a>

The link’s destination is specified in the href attribute.

Attributes are used to provide additional information about HTML elements.

You will learn more about attributes in a later chapter.


HTML Images

HTML images are defined with the <img> tag.

The source file (src), alternative text (alt), width, and height are provided as attributes:

Example

<img src="apostube.jpg" alt="apostube.com" width="100" height="150">


HTML Elements

The HTML element is everything from the start tag to the end tag:

<tagname>Content goes here...</tagname>

Examples of some HTML elements:

<h1>My First Heading</h1>

<p>My first paragraph.</p>
Start tag Element content End tag
<h1> My First Heading </h1>
<p> My first paragraph. </p>
<br> none none

Note: Some HTML elements have no content (like the <br> element). These elements are called empty elements. Empty elements do not have an end tag!


Nested HTML Elements

HTML elements can be nested (this means that elements can contain other elements).

All HTML documents consist of nested HTML elements.

The following example contains four HTML elements (<html><body><h1> and <p>):

Example

<!DOCTYPE html>
<html>
<body>

<h1>My First Heading</h1>
<p>My first paragraph.</p>

</body>
</html>

Example Explained

The <html> element is the root element and it defines the whole HTML document.

It has a start tag <html> and an end tag </html>.

Then, inside the <html> element there is a <body> element:

<body>

<h1>My First Heading</h1>
<p>My first paragraph.</p>

</body>

The <body> element defines the document’s body.

It has a start tag <body> and an end tag </body>.

Then, inside the <body> element there are two other elements: <h1> and <p>:

<h1>My First Heading</h1>
<p>My first paragraph.</p>

The <h1> element defines a heading.

It has a start tag <h1> and an end tag </h1>:

<h1>My First Heading</h1>

The <p> element defines a paragraph.

It has a start tag <p> and an end tag </p>:

<p>My first paragraph.</p>

Never Skip the End Tag

Some HTML elements will display correctly, even if you forget the end tag:

Example

<html>
<body>

<p>This is a paragraph
<p>This is a paragraph

</body>
</html>

Empty HTML Elements

HTML elements with no content are called empty elements.

The <br> tag defines a line break, and is an empty element without a closing tag:

Example

<p>This is a <br> paragraph with a line break.</p>

HTML Attributes

  • All HTML elements can have attributes
  • Attributes provide additional information about elements
  • Attributes are always specified in the start tag
  • Attributes usually come in name/value pairs like: name=”value”

The href Attribute

The <a> tag defines a hyperlink. The href attribute specifies the URL of the page the link goes to:

Example

<a href="https://www.apostube.com">Visit Swift Games</a>

The src Attribute

The <img> tag is used to embed an image in an HTML page. The src attribute specifies the path to the image to be displayed:

Example

<img src="img_girl.jpg">

There are two ways to specify the URL in the src attribute:

1. Absolute URL – Links to an external image that is hosted on another website. Example: src=”https://www.apostube.com/img_girl.jpg”.

Notes: External images might be under copyright. If you do not get permission to use it, you may be in violation of copyright laws. In addition, you cannot control external images; it can suddenly be removed or changed.

2. Relative URL – Links to an image that is hosted within the website. Here, the URL does not include the domain name. If the URL begins without a slash, it will be relative to the current page. Example: src=”img_girl.jpg”. If the URL begins with a slash, it will be relative to the domain. Example: src=”/images/img_girl.jpg”.

Tip: It is almost always best to use relative URLs. They will not break if you change domain.


The width and height Attributes

The <img> tag should also contain the width and height attributes, which specifies the width and height of the image (in pixels):

Example

<img src="img_girl.jpg" width="500" height="600">

The alt Attribute

The required alt attribute for the <img> tag specifies an alternate text for an image, if the image for some reason cannot be displayed. This can be due to slow connection, or an error in the src attribute, or if the user uses a screen reader.

Example

<img src="img_girl.jpg" alt="Girl with a jacket">

Example

See what happens if we try to display an image that does not exist:

<img src="img_typo.jpg" alt="Girl with a jacket">

The style Attribute

The style attribute is used to add styles to an element, such as color, font, size, and more.

Example

<p style="color:red;">This is a red paragraph.</p>

The lang Attribute

You should always include the lang attribute inside the <html> tag, to declare the language of the Web page. This is meant to assist search engines and browsers.

The following example specifies English as the language:

<!DOCTYPE html>
<html lang="en">
<body>
...
</body>
</html>

Country codes can also be added to the language code in the lang attribute. So, the first two characters define the language of the HTML page, and the last two characters define the country.

The following example specifies English as the language and United States as the country:

<!DOCTYPE html>
<html lang="en-US">
<body>
...
</body>
</html>

The title Attribute

The title attribute defines some extra information about an element.

The value of the title attribute will be displayed as a tooltip when you mouse over the element:

Example

<p title="I'm a tooltip">This is a paragraph.</p>

HTML Headings (#3)


HTML headings are titles or subtitles that you want to display on a webpage.

Example

Heading 1

Heading 2

Heading 3

Heading 4

Heading 5
HEADING 6

HTML Headings

HTML headings are defined with the <h1> to <h6> tags.

<h1> defines the most important heading. <h6> defines the least important heading.

Example

<h1>Heading 1</h1>
<h2>Heading 2</h2>
<h3>Heading 3</h3>
<h4>Heading 4</h4>
<h5>Heading 5</h5>
<h6>Heading 6</h6>

Note: Browsers automatically add some white space (a margin) before and after a heading.


Headings Are Important

Search engines use the headings to index the structure and content of your web pages.

Users often skim a page by its headings. It is important to use headings to show the document structure.

<h1> headings should be used for main headings, followed by <h2> headings, then the less important <h3>, and so on.

Note: Use HTML headings for headings only. Don’t use headings to make text BIG or bold.


Bigger Headings

Each HTML heading has a default size. However, you can specify the size for any heading with the style attribute, using the CSS font-size property:

Example

<h1 style="font-size:60px;">Heading 1</h1>

HTML Paragraphs

The HTML <p> element defines a paragraph.

A paragraph always starts on a new line, and browsers automatically add some white space (a margin) before and after a paragraph.

Example

<p>This is a paragraph.</p>
<p>This is another paragraph.</p>

HTML Display

You cannot be sure how HTML will be displayed.

Large or small screens, and resized windows will create different results.

With HTML, you cannot change the display by adding extra spaces or extra lines in your HTML code.

The browser will automatically remove any extra spaces and lines when the page is displayed:

Example

<p>
This paragraph
contains a lot of lines
in the source code,
but the browser
ignores it.
</p>

<p>
This paragraph
contains         a lot of spaces
in the source         code,
but the        browser
ignores it.
</p>

HTML Horizontal Rules

The <hr> tag defines a thematic break in an HTML page, and is most often displayed as a horizontal rule.

The <hr> element is used to separate content (or define a change) in an HTML page:

Example

<h1>This is heading 1</h1>
<p>This is some text.</p>
<hr>
<h2>This is heading 2</h2>
<p>This is some other text.</p>
<hr>

The <hr> tag is an empty tag, which means that it has no end tag.


HTML Line Breaks

The HTML <br> element defines a line break.

Use <br> if you want a line break (a new line) without starting a new paragraph:

Example

<p>This is<br>a paragraph<br>with line breaks.</p>

The <br> tag is an empty tag, which means that it has no end tag.


The Poem Problem

This poem will display on a single line:

Example

<p>
  My Bonnie lies over the ocean.

  My Bonnie lies over the sea.

  My Bonnie lies over the ocean.

  Oh, bring back my Bonnie to me.
</p>

Solution – The HTML <pre> Element

The HTML <pre> element defines preformatted text.

The text inside a <pre> element is displayed in a fixed-width font (usually Courier), and it preserves both spaces and line breaks:

Example

<pre>
  My Bonnie lies over the ocean.

  My Bonnie lies over the sea.

  My Bonnie lies over the ocean.

  Oh, bring back my Bonnie to me.
</pre>

HTML Styles (#4)

The HTML style attribute is used to add styles to an element, such as color, font, size, and more.


Example

I am Red

I am Blue

I am Big


The HTML Style Attribute

Setting the style of an HTML element, can be done with the style attribute.

The HTML style attribute has the following syntax:

<tagname style="property:value;">

Background Color

The CSS background-color property defines the background color for an HTML element.

Example

Set the background color for a page to powderblue:

<body style="background-color:powderblue;">

<h1>This is a heading</h1>
<p>This is a paragraph.</p>

</body>

Example

Set background color for two different elements:

<body>

<h1 style="background-color:powderblue;">This is a heading</h1>
<p style="background-color:tomato;">This is a paragraph.</p>

</body>

Text Color

The CSS color property defines the text color for an HTML element:

Example

<h1 style="color:blue;">This is a heading</h1>
<p style="color:red;">This is a paragraph.</p>

Fonts

The CSS font-family property defines the font to be used for an HTML element:

Example

<h1 style="font-family:verdana;">This is a heading</h1>
<p style="font-family:courier;">This is a paragraph.</p>

Text Size

The CSS font-size property defines the text size for an HTML element:

Example

<h1 style="font-size:300%;">This is a heading</h1>
<p style="font-size:160%;">This is a paragraph.</p>

Text Alignment

The CSS text-align property defines the horizontal text alignment for an HTML element:

Example

<h1 style="text-align:center;">Centered Heading</h1>
<p style="text-align:center;">Centered paragraph.</p>

Chapter Summary

  • Use the style attribute for styling HTML elements
  • Use background-color for background color
  • Use color for text colors
  • Use font-family for text fonts
  • Use font-size for text sizes
  • Use text-align for text alignment

HTML Text Formatting (#5)

HTML contains several elements for defining text with a special meaning.


Example

This text is bold

This text is italic

This is subscript and superscript


HTML Formatting Elements

Formatting elements were designed to display special types of text:

  • <b> – Bold text
  • <strong> – Important text
  • <i> – Italic text
  • <em> – Emphasized text
  • <mark> – Marked text
  • <small> – Smaller text
  • <del> – Deleted text
  • <ins> – Inserted text
  • <sub> – Subscript text
  • <sup> – Superscript text

HTML <b> and <strong> Elements

The HTML <b> element defines bold text, without any extra importance.

Example

<b>This text is bold</b>

The HTML <strong> element defines text with strong importance. The content inside is typically displayed in bold.

Example

<strong>This text is important!</strong>

HTML <i> and <em> Elements

The HTML <i> element defines a part of text in an alternate voice or mood. The content inside is typically displayed in italic.

Tip: The <i> tag is often used to indicate a technical term, a phrase from another language, a thought, a ship name, etc.

Example

<i>This text is italic</i>

The HTML <em> element defines emphasized text. The content inside is typically displayed in italic.

Tip: A screen reader will pronounce the words in <em> with an emphasis, using verbal stress.

Example

<em>This text is emphasized</em>

HTML <small> Element

The HTML <small> element defines smaller text:

Example

<small>This is some smaller text.</small>

HTML <mark> Element

The HTML <mark> element defines text that should be marked or highlighted:

Example

<p>Do not forget to buy <mark>milk</mark> today.</p>

HTML <del> Element

The HTML <del> element defines text that has been deleted from a document. Browsers will usually strike a line through deleted text:

Example

<p>My favorite color is <del>blue</del> red.</p>

HTML <ins> Element

The HTML <ins> element defines a text that has been inserted into a document. Browsers will usually underline inserted text:

Example

<p>My favorite color is <del>blue</del> <ins>red</ins>.</p>

HTML <sub> Element

The HTML <sub> element defines subscript text. Subscript text appears half a character below the normal line, and is sometimes rendered in a smaller font. Subscript text can be used for chemical formulas, like H2O:

Example

<p>This is <sub>subscripted</sub> text.</p>

HTML <sup> Element

The HTML <sup> element defines superscript text. Superscript text appears half a character above the normal line, and is sometimes rendered in a smaller font. Superscript text can be used for footnotes, like WWW[1]:

Example

<p>This is <sup>superscripted</sup> text.</p>

HTML Quotation and Citation Elements (#6)

In this chapter we will go through the <blockquote>,<q><abbr><address><cite>, and <bdo> HTML elements.


Example

Here is a quote from WWF’s website:

For nearly 60 years, WWF has been protecting the future of nature. The world’s leading conservation organization, WWF works in 100 countries and is supported by more than one million members in the United States and close to five million globally.


HTML <blockquote> for Quotations

The HTML <blockquote> element defines a section that is quoted from another source.

Browsers usually indent <blockquote> elements.

Example

<p>Here is a quote from WWF's website:</p>
<blockquote cite="http://www.worldwildlife.org/who/index.html">
For 50 years, WWF has been protecting the future of nature.
The world's leading conservation organization,
WWF works in 100 countries and is supported by
1.2 million members in the United States and
close to 5 million globally.
</blockquote>

HTML <q> for Short Quotations

The HTML <q> tag defines a short quotation.

Browsers normally insert quotation marks around the quotation.

Example

<p>WWF's goal is to: <q>Build a future where people live in harmony with nature.</q></p>

HTML <abbr> for Abbreviations

The HTML <abbr> tag defines an abbreviation or an acronym, like “HTML”, “CSS”, “Mr.”, “Dr.”, “ASAP”, “ATM”.

Marking abbreviations can give useful information to browsers, translation systems and search-engines.

Tip: Use the global title attribute to show the description for the abbreviation/acronym when you mouse over the element.

Example

<p>The <abbr title="World Health Organization">WHO</abbr> was founded in 1948.</p>

HTML <address> for Contact Information

The HTML <address> tag defines the contact information for the author/owner of a document or an article.

The contact information can be an email address, URL, physical address, phone number, social media handle, etc.

The text in the <address> element usually renders in italic, and browsers will always add a line break before and after the <address> element.

Example

<address>
Written by John Doe.<br>
Visit us at:<br>
Example.com<br>
Box 564, Disneyland<br>
USA
</address>

HTML <cite> for Work Title

The HTML <cite> tag defines the title of a creative work (e.g. a book, a poem, a song, a movie, a painting, a sculpture, etc.).

Note: A person’s name is not the title of a work.

The text in the <cite> element usually renders in italic.

Example

<p><cite>The Scream</cite> by Edvard Munch. Painted in 1893.</p>

HTML <bdo> for Bi-Directional Override

BDO stands for Bi-Directional Override.

The HTML <bdo> tag is used to override the current text direction:

Example

<bdo dir="rtl">This text will be written from right to left</bdo>

HTML Comments (#7)

HTML comments are not displayed in the browser, but they can help document your HTML source code.


HTML Comment Tag

You can add comments to your HTML source by using the following syntax:

<!-- Write your comments here -->

Notice that there is an exclamation point (!) in the start tag, but not in the end tag.

Note: Comments are not displayed by the browser, but they can help document your HTML source code.


Add Comments

With comments you can place notifications and reminders in your HTML code:

Example

<!-- This is a comment -->

<p>This is a paragraph.</p>

<!-- Remember to add more information here -->

Hide Content

Comments can be used to hide content.

Which can be helpful if you hide content temporarily:

Example

<p>This is a paragraph.</p>

<!-- <p>This is another paragraph </p> -->

<p>This is a paragraph too.</p>

You can also hide more than one line, everything between the <!-- and the --> will be hidden from the display.

Example

Hide a section of HTML code:

<p>This is a paragraph.</p>
<!--
<p>Look at this cool image:</p>
<img border="0" src="pic_trulli.jpg" alt="Trulli">
-->
<p>This is a paragraph too.</p>

Comments are also great for debugging HTML, because you can comment out HTML lines of code, one at a time, to search for errors.


Hide Inline Content

Comments can be used to hide parts in the middle of the HTML code.

Example

Hide a part of a paragaph:

<p>This <!-- great text --> is a paragraph.</p>

HTML Colors (#8)

HTML colors are specified with predefined color names, or with RGB, HEX, HSL, RGBA, or HSLA values.


Color Names

In HTML, a color can be specified by using a color name:

Tomato
Orange
DodgerBlue
MediumSeaGreen
Gray
SlateBlue
Violet
LightGray

HTML supports 140 standard color names.


Background Color

You can set the background color for HTML elements:

Hello World
Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh euismod tincidunt ut laoreet dolore magna aliquam erat volutpat. Ut wisi enim ad minim veniam, quis nostrud exerci tation ullamcorper suscipit lobortis nisl ut aliquip ex ea commodo consequat.

Example

<h1 style="background-color:DodgerBlue;">Hello World</h1>
<p style="background-color:Tomato;">Lorem ipsum...</p>

Text Color

You can set the color of text:

Hello World

Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh euismod tincidunt ut laoreet dolore magna aliquam erat volutpat.

Ut wisi enim ad minim veniam, quis nostrud exerci tation ullamcorper suscipit lobortis nisl ut aliquip ex ea commodo consequat.

Example

<h1 style="color:Tomato;">Hello World</h1>
<p style="color:DodgerBlue;">Lorem ipsum...</p>
<p style="color:MediumSeaGreen;">Ut wisi enim...</p>

Border Color

You can set the color of borders:

Hello World

Hello World

Hello World

Example

<h1 style="border:2px solid Tomato;">Hello World</h1>
<h1 style="border:2px solid DodgerBlue;">Hello World</h1>
<h1 style="border:2px solid Violet;">Hello World</h1>

Color Values

In HTML, colors can also be specified using RGB values, HEX values, HSL values, RGBA values, and HSLA values.

The following three <div> elements have their background color set with RGB, HEX, and HSL values:

rgb(255, 99, 71)
#ff6347
hsl(9, 100%, 64%)

The following two <div> elements have their background color set with RGBA and HSLA values, which adds an Alpha channel to the color (here we have 50% transparency):

rgba(255, 99, 71, 0.5)
hsla(9, 100%, 64%, 0.5)

Example

<h1 style="background-color:rgb(255, 99, 71);">...</h1>
<h1 style="background-color:#ff6347;">...</h1>
<h1 style="background-color:hsl(9, 100%, 64%);">...</h1>

<h1 style="background-color:rgba(255, 99, 71, 0.5);">...</h1>
<h1 style="background-color:hsla(9, 100%, 64%, 0.5);">...</h1>

HTML Styles – CSS

CSS stands for Cascading Style Sheets.

CSS saves a lot of work. It can control the layout of multiple web pages all at once.


CSS = Styles and Colors (#9)

Manipulate Text
Colors,  Boxes

What is CSS?

Cascading Style Sheets (CSS) is used to format the layout of a webpage.

With CSS, you can control the color, font, the size of text, the spacing between elements, how elements are positioned and laid out, what background images or background colors are to be used, different displays for different devices and screen sizes, and much more!

Tip: The word cascading means that a style applied to a parent element will also apply to all children elements within the parent. So, if you set the color of the body text to “blue”, all headings, paragraphs, and other text elements within the body will also get the same color (unless you specify something else)!


Using CSS

CSS can be added to HTML documents in 3 ways:

  • Inline – by using the style attribute inside HTML elements
  • Internal – by using a <style> element in the <head> section
  • External – by using a <link> element to link to an external CSS file

The most common way to add CSS, is to keep the styles in external CSS files. However, in this tutorial we will use inline and internal styles, because this is easier to demonstrate, and easier for you to try it yourself.


Inline CSS

An inline CSS is used to apply a unique style to a single HTML element.

An inline CSS uses the style attribute of an HTML element.

The following example sets the text color of the <h1> element to blue, and the text color of the <p> element to red:

Example

<h1 style="color:blue;">A Blue Heading</h1>

<p style="color:red;">A red paragraph.</p>

Internal CSS

An internal CSS is used to define a style for a single HTML page.

An internal CSS is defined in the <head> section of an HTML page, within a <style> element.

The following example sets the text color of ALL the <h1> elements (on that page) to blue, and the text color of ALL the <p> elements to red. In addition, the page will be displayed with a “powderblue” background color:

Example

<!DOCTYPE html>
<html>
<head>
<style>
body {background-color: powderblue;}
h1   {color: blue;}
p    {color: red;}</style>
</head>
<body>

<h1>This is a heading</h1>
<p>This is a paragraph.</p>

</body>
</html>

External CSS

An external style sheet is used to define the style for many HTML pages.

To use an external style sheet, add a link to it in the <head> section of each HTML page:

Example

<!DOCTYPE html>
<html>
<head>
  <link rel="stylesheet" href="styles.css">
</head>
<body>

<h1>This is a heading</h1>
<p>This is a paragraph.</p>

</body>
</html>

The external style sheet can be written in any text editor. The file must not contain any HTML code, and must be saved with a .css extension.

Here is what the “styles.css” file looks like:

“styles.css”:

body {
  background-color: powderblue;}
h1 {
  color: blue;}{
  color: red;}

Tip: With an external style sheet, you can change the look of an entire web site, by changing one file!


CSS Colors, Fonts and Sizes

Here, we will demonstrate some commonly used CSS properties. You will learn more about them later.

The CSS color property defines the text color to be used.

The CSS font-family property defines the font to be used.

The CSS font-size property defines the text size to be used.

Example

Use of CSS color, font-family and font-size properties:

<!DOCTYPE html>
<html>
<head>
<style>
h1 {
  color: blue;
  font-family: verdana;
  font-size: 300%;}{
  color: red;
  font-family: courier;
  font-size: 160%;}</style>
</head>
<body>

<h1>This is a heading</h1>
<p>This is a paragraph.</p>

</body>
</html>

CSS Border

The CSS border property defines a border around an HTML element.

Tip: You can define a border for nearly all HTML elements.

Example

Use of CSS border property:

{
  border: 2px solid powderblue;}

CSS Padding

The CSS padding property defines a padding (space) between the text and the border.

Example

Use of CSS border and padding properties:

{
  border: 2px solid powderblue;
  padding: 30px;}

CSS Margin

The CSS margin property defines a margin (space) outside the border.

Example

Use of CSS border and margin properties:

{
  border: 2px solid powderblue;
  margin: 50px;}

Link to External CSS

External style sheets can be referenced with a full URL or with a path relative to the current web page.

Example

This example uses a full URL to link to a style sheet:

<link rel=”stylesheet” href=”https://www.w3schools.com/html/styles.css”>

Example

This example links to a style sheet located in the html folder on the current web site:

<link rel="stylesheet" href="/html/styles.css">

Example

This example links to a style sheet located in the same folder as the current page:

<link rel="stylesheet" href="styles.css">

Chapter Summary

  • Use the HTML style attribute for inline styling
  • Use the HTML <style> element to define internal CSS
  • Use the HTML <link> element to refer to an external CSS file
  • Use the HTML <head> element to store <style> and <link> elements
  • Use the CSS color property for text colors
  • Use the CSS font-family property for text fonts
  • Use the CSS font-size property for text sizes
  • Use the CSS border property for borders
  • Use the CSS padding property for space inside the border
  • Use the CSS margin property for space outside the border

HTML Links (#10)

Links are found in nearly all web pages. Links allow users to click their way from page to page.


HTML Links – Hyperlinks

HTML links are hyperlinks.

You can click on a link and jump to another document.

When you move the mouse over a link, the mouse arrow will turn into a little hand.

Note: A link does not have to be text. A link can be an image or any other HTML element!


HTML Links – Syntax

The HTML <a> tag defines a hyperlink. It has the following syntax:

<a href="url">link text</a>

The most important attribute of the <a> element is the href attribute, which indicates the link’s destination.

The link text is the part that will be visible to the reader.

Clicking on the link text, will send the reader to the specified URL address.

Example

This example shows how to create a link to apostube.com:

<a href="https://www.apostube.com/">Visit apostube.com!</a>

By default, links will appear as follows in all browsers:

  • An unvisited link is underlined and blue
  • A visited link is underlined and purple
  • An active link is underlined and red

Tip: Links can of course be styled with CSS, to get another look!


HTML Links – The target Attribute

By default, the linked page will be displayed in the current browser window. To change this, you must specify another target for the link.

The target attribute specifies where to open the linked document.

The target attribute can have one of the following values:

  • _self – Default. Opens the document in the same window/tab as it was clicked
  • _blank – Opens the document in a new window or tab
  • _parent – Opens the document in the parent frame
  • _top – Opens the document in the full body of the window

Example

Use target=”_blank” to open the linked document in a new browser window or tab:

<a href="https://www.apostube.com/" target="_blank">Visit Apostube!</a>

Absolute URLs vs. Relative URLs

Both examples above are using an absolute URL (a full web address) in the href attribute.

A local link (a link to a page within the same website) is specified with a relative URL (without the “https://www” part):

Example

<h2>Absolute URLs</h2>
<p><a href="https://www.apostube.com/">AposTube</a></p>
<p><a href="https://www.google.com/">Google</a></p>

<h2>Relative URLs</h2>
<p><a href="html_images.asp">HTML Images</a></p>
<p><a href="/css/default.asp">CSS Tutorial</a></p>

HTML Links – Use an Image as a Link

To use an image as a link, just put the <img> tag inside the <a> tag:

Example

<a href="default.asp">
<img src="smiley.gif" alt="HTML tutorial" style="width:42px;height:42px;">
</a>

Link to an Email Address

Use mailto: inside the href attribute to create a link that opens the user’s email program (to let them send a new email):

Example

<a href="mail to:someone@example.com">Send email</a>

Button as a Link

To use an HTML button as a link, you have to add some JavaScript code.

JavaScript allows you to specify what happens at certain events, such as a click of a button:

Example

<button onclick="document.location='default.asp'">HTML Tutorial</button>

Link Titles

The title attribute specifies extra information about an element. The information is most often shown as a tooltip text when the mouse moves over the element.

Example

<a href="https://www.apostube.com/html/" title="Go to Apostube HTML section">Visit our HTML Tutorial</a>

More on Absolute URLs and Relative URLs

Example

Use a full URL to link to a web page:

<a href="https://www.apostube.com/category/html">Learn HTML</a>

Example

Link to a page located in the html folder on the current web site:

<a href="/html/default.asp">HTML tutorial</a>

Example

Link to a page located in the same folder as the current page:

<a href="default.asp">HTML tutorial</a>

Chapter Summary

  • Use the <a> element to define a link
  • Use the href attribute to define the link address
  • Use the target attribute to define where to open the linked document
  • Use the <img> element (inside <a>) to use an image as a link
  • Use the mailto: scheme inside the href attribute to create a link that opens the user’s email program

HTML Link Tags

Tag Description
<a> Defines a hyperlink

HTML Images (#11)

Discover the magic of AlberobelloUnidentified person in cold weather.

Images can improve the design and the appearance of a web page.


Example

<img src="img_chania.jpg" alt="Flowers in Chania">

Example

<img src="img_girl.jpg" alt="Girl in a jacket">

Example

<img src="pic_trulli.jpg" alt="Italian Trulli">

HTML Images Syntax

The HTML <img> tag is used to embed an image in a web page.

Images are not technically inserted into a web page; images are linked to web pages. The <img> tag creates a holding space for the referenced image.

The <img> tag is empty, it contains attributes only, and does not have a closing tag.

The <img> tag has two required attributes:

  • src – Specifies the path to the image
  • alt – Specifies an alternate text for the image

Syntax

<img src="url" alt="alternatetext">

The src Attribute

The required src attribute specifies the path (URL) to the image.

Note: When a web page loads, it is the browser, at that moment, that gets the image from a web server and inserts it into the page. Therefore, make sure that the image actually stays in the same spot in relation to the web page, otherwise your visitors will get a broken link icon. The broken link icon and the alt text are shown if the browser cannot find the image.

Example

<img src="img_chania.jpg" alt="Flowers in Chania">

The alt Attribute

The required alt attribute provides an alternate text for an image, if the user for some reason cannot view it (because of slow connection, an error in the src attribute, or if the user uses a screen reader).

The value of the alt attribute should describe the image:

Example

<img src="img_chania.jpg" alt="Flowers in Chania">

If a browser cannot find an image, it will display the value of the alt attribute:

Example

<img src="wrongname.gif" alt="Flowers in Chania">

Tip: A screen reader is a software program that reads the HTML code, and allows the user to “listen” to the content. Screen readers are useful for people who are visually impaired or learning disabled.


Image Size – Width and Height

You can use the style attribute to specify the width and height of an image.

Example

<img src="img_girl.jpg" alt="Girl in a jacket" style="width:500px;height:600px;">

Alternatively, you can use the width and height attributes:

Example

<img src="img_girl.jpg" alt="Girl in a jacket" width="500" height="600">

The width and height attributes always define the width and height of the image in pixels.

Note: Always specify the width and height of an image. If width and height are not specified, the web page might flicker while the image loads.


Width and Height, or Style?

The widthheight, and style attributes are all valid in HTML.

However, we suggest using the style attribute. It prevents styles sheets from changing the size of images:

Example

<!DOCTYPE html>
<html>
<head>
<style>
img {
  width: 100%;}</style>
</head>
<body>

<img src="html5.gif" alt="HTML5 Icon" width="128" height="128">

<img src="html5.gif" alt="HTML5 Icon" style="width:128px;height:128px;">

</body>
</html>

Images in Another Folder

If you have your images in a sub-folder, you must include the folder name in the src attribute:

Example

<img src="/images/html5.gif" alt="HTML5 Icon" style="width:128px;height:128px;">

Images on Another Server/Website

Some web sites point to an image on another server.

To point to an image on another server, you must specify an absolute (full) URL in the src attribute:

Example

<img src="https://www.apostube.com/images.jpg" alt="apostube.com">

Notes on external images: External images might be under copyright. If you do not get permission to use it, you may be in violation of copyright laws. In addition, you cannot control external images; it can suddenly be removed or changed.


Animated Images

HTML allows animated GIFs:

Example

<img src="programming.gif" alt="Computer Man" style="width:48px;height:48px;">

Image as a Link

To use an image as a link, put the <img> tag inside the <a> tag:

Example

<a href="default.asp">
  <img src="smiley.gif" alt="HTML tutorial" style="width:42px;height:42px;">
</a>

Image Floating

Use the CSS float property to let the image float to the right or to the left of a text:

Example

<p><img src="smiley.gif" alt="Smiley face" style="float:right;width:42px;height:42px;">
The image will float to the right of the text.</p>

<p><img src="smiley.gif" alt="Smiley face" style="float:left;width:42px;height:42px;">
The image will float to the left of the text.</p>

Common Image Formats

Here are the most common image file types, which are supported in all browsers (Chrome, Edge, Firefox, Safari, Opera):

Abbreviation File Format File Extension
APNG Animated Portable Network Graphics .apng
GIF Graphics Interchange Format .gif
ICO Microsoft Icon .ico, .cur
JPEG Joint Photographic Expert Group image .jpg, .jpeg, .jfif, .pjpeg, .pjp
PNG Portable Network Graphics .png
SVG Scalable Vector Graphics .svg

Chapter Summary

  • Use the HTML <img> element to define an image
  • Use the HTML src attribute to define the URL of the image
  • Use the HTML alt attribute to define an alternate text for an image, if it cannot be displayed
  • Use the HTML width and height attributes or the CSS width and height properties to define the size of the image
  • Use the CSS float property to let the image float to the left or to the right

Note: Loading large images takes time, and can slow down your web page. Use images carefully.


HTML Image Maps (#12)

With HTML image maps, you can create clickable areas on an image.


Image Maps

The HTML <map> tag defines an image map. An image map is an image with clickable areas. The areas are defined with one or more <area> tags.

Try to click on the computer, phone, or the cup of coffee in the image below:

Workplace

Venus

Example

Here is the HTML source code for the image map above:

<img src="workplace.jpg" alt="Workplace" usemap="#workmap">

<map name="workmap">
  <area shape="rect" coords="34,44,270,350" alt="Computer" href="computer.htm">
  <area shape="rect" coords="290,172,333,250" alt="Phone" href="phone.htm">
  <area shape="circle" coords="337,300,44" alt="Coffee" href="coffee.htm">
</map>

How Does it Work?

The idea behind an image map is that you should be able to perform different actions depending on where in the image you click.

To create an image map you need an image, and some HTML code that describes the clickable areas.


The Image

The image is inserted using the <img> tag. The only difference from other images is that you must add a usemap attribute:

<img src="workplace.jpg" alt="Workplace" usemap="#workmap">

The usemap value starts with a hash tag # followed by the name of the image map, and is used to create a relationship between the image and the image map.

Tip: You can use any image as an image map!


Create Image Map

Then, add a <map> element.

The <map> element is used to create an image map, and is linked to the image by using the required name attribute:

<map name="workmap">

The name attribute must have the same value as the <img>‘s usemap attribute .


The Areas

Then, add the clickable areas.

A clickable area is defined using an <area> element.

Shape

You must define the shape of the clickable area, and you can choose one of these values:

  • rect – defines a rectangular region
  • circle – defines a circular region
  • poly – defines a polygonal region
  • default – defines the entire region

You must also define some coordinates to be able to place the clickable area onto the image.


Shape=”rect”

The coordinates for shape="rect" come in pairs, one for the x-axis and one for the y-axis.

So, the coordinates 34,44 is located 34 pixels from the left margin and 44 pixels from the top:

Workplace

The coordinates 270,350 is located 270 pixels from the left margin and 350 pixels from the top:

Workplace

Now we have enough data to create a clickable rectangular area:

Example

<area shape="rect" coords="34, 44, 270, 350" href="computer.htm">

This is the area that becomes clickable and will send the user to the page “computer.htm”:

Workplace


Shape=”circle”

To add a circle area, first locate the coordinates of the center of the circle:

337,300

Workplace

Then specify the radius of the circle:

44 pixels

Workplace

Now you have enough data to create a clickable circular area:

Example

<area shape="circle" coords="337, 300, 44" href="coffee.htm">

This is the area that becomes clickable and will send the user to the page “coffee.htm”:

Workplace


Shape=”poly”

The shape="poly" contains several coordinate points, which creates a shape formed with straight lines (a polygon).

This can be used to create any shape.

Like maybe a croissant shape!

How can we make the croissant in the image below become a clickable link?

French Food

We have to find the x and y coordinates for all edges of the croissant:

French Food

The coordinates come in pairs, one for the x-axis and one for the y-axis:

Example

<area shape="poly" coords="140,121,181,116,204,160,204,222,191,270,140,329,85,355,58,352,37,322,40,259,103,161,128,147" href="croissant.htm">

This is the area that becomes clickable and will send the user to the page “croissant.htm”:

French Food


Image Map and JavaScript

A clickable area can also trigger a JavaScript function.

Add a click event to the <area> element to execute a JavaScript function:

Example

Here, we use the onclick attribute to execute a JavaScript function when the area is clicked:

<map name="workmap">
  <area shape="circle" coords="337,300,44" href="coffee.htm" onclick="myFunction()">
</map>

<script>function myFunction() {
  alert("You clicked the coffee cup!");
}
</script>

Chapter Summary

  • Use the HTML <map> element to define an image map
  • Use the HTML <area> element to define the clickable areas in the image map
  • Use the HTML usemap attribute of the <img> element to point to an image map

HTML Background Images (#13)

A background image can be specified for almost any HTML element.


Background Image on a HTML element

To add a background image on an HTML element, use the HTML style attribute and the CSS background-image property:

Example

Add a background image on a HTML element:

<p style=”background-image: url(‘img_girl.jpg’);”>

You can also specify the background image in the <style> element, in the <head> section:

Example

Specify the background image in the <style> element:

<style>{
  background-image: url('img_girl.jpg');}</style>

Background Image on a Page

If you want the entire page to have a background image, you must specify the background image on the <body> element:

Example

Add a background image for the entire page:

<style>
body {
  background-image: url('img_girl.jpg');}</style>

Background Repeat

If the background image is smaller than the element, the image will repeat itself, horizontally and vertically, until it reaches the end of the element:

Example

<style>
body {
  background-image: url('example_img_girl.jpg');}</style>

To avoid the background image from repeating itself, set the background-repeat property to no-repeat.

Example

<style>
body {
  background-image: url('example_img_girl.jpg');
  background-repeat: no-repeat;}</style>

Background Cover

If you want the background image to cover the entire element, you can set the background-size property to cover.

Also, to make sure the entire element is always covered, set the background-attachment property to fixed:

This way, the background image will cover the entire element, with no stretching (the image will keep its original proportions):

Example

<style>
body {
  background-image: url('img_girl.jpg');
  background-repeat: no-repeat;
  background-attachment: fixed;
  background-size: cover;}</style>

Background Stretch

If you want the background image to stretch to fit the entire element, you can set the background-size property to 100% 100%:

Try resizing the browser window, and you will see that the image will stretch, but always cover the entire element.

Example

<style>
body {
  background-image: url('img_girl.jpg');
  background-repeat: no-repeat;
  background-attachment: fixed;
  background-size: 100% 100%;}</style>

HTML <picture> Element (#14)

The HTML <picture> element allows you to display different pictures for different devices or screen sizes.



The HTML <picture> Element

The HTML <picture> element gives web developers more flexibility in specifying image resources.

The <picture> element contains one or more <source> elements, each referring to different images through the srcset attribute. This way the browser can choose the image that best fits the current view and/or device.

Each <source> element has a media attribute that defines when the image is the most suitable.

Example

Show different images for different screen sizes:

<picture>
  <source media="(min-width: 650px)" srcset="img_food.jpg">
  <source media="(min-width: 465px)" srcset="img_car.jpg">
  <img src="img_girl.jpg">
</picture>

Note: Always specify an <img> element as the last child element of the <picture> element. The <img> element is used by browsers that do not support the <picture> element, or if none of the <source> tags match.


When to use the Picture Element

There are two main purposes for the <picture> element:

1. Bandwidth

If you have a small screen or device, it is not necessary to load a large image file. The browser will use the first <source> element with matching attribute values, and ignore any of the following elements.

2. Format Support

Some browsers or devices may not support all image formats. By using the <picture> element, you can add images of all formats, and the browser will use the first format it recognizes, and ignore any of the following elements.

Example

The browser will use the first image format it recognizes:

<picture>
  <source srcset="img_avatar.png">
  <source srcset="img_girl.jpg">
  <img src="img_beatles.gif" alt="Beatles" style="width:auto;">
</picture>
Note: The browser will use the first <source> element with matching attribute values, and ignore any following <source> elements.

HTML Favicon (#15)

A favicon is a small image displayed next to the page title in the browser tab.


How To Add a Favicon in HTML

You can use any image you like as your favicon. You can also create your own favicon on sites like https://www.favicon.cc.

Tip: A favicon is a small image, so it should be a simple image with high contrast.

A favicon image is displayed to the left of the page title in the browser tab, like this:

To add a favicon to your website, either save your favicon image to the root directory of your webserver, or create a folder in the root directory called images, and save your favicon image in this folder. A common name for a favicon image is “favicon.ico”.

Next, add a <link> element to your “index.html” file, after the <title> element, like this:

Example

<!DOCTYPE html>
<html>
<head>
  <title>My Page Title</title>
  <link rel="icon" type="image/x-icon" href="/images/favicon.ico">
</head>
<body>

<h1>This is a Heading</h1>
<p>This is a paragraph.</p>

</body>
</html>

Now, save the “index.html” file and reload it in your browser. Your browser tab should now display your favicon image to the left of the page title.


Favicon File Format Support

The following table shows the file format support for a favicon image:

Browser ICO PNG GIF JPEG SVG
Edge Yes Yes Yes Yes Yes
Chrome Yes Yes Yes Yes Yes
Firefox Yes Yes Yes Yes Yes
Opera Yes Yes Yes Yes Yes
Safari Yes Yes Yes Yes Yes

Chapter Summary

  • Use the HTML <link> element to insert a favicon

HTML Tables (#16)

HTML tables allow web developers to arrange data into rows and columns.

Example

Company Contact Country
Alfreds Futterkiste Maria Anders Germany
Centro comercial Moctezuma Francisco Chang Mexico
Ernst Handel Roland Mendel Austria
Island Trading Helen Bennett UK
Laughing Bacchus Winecellars Yoshi Tannamuri Canada
Magazzini Alimentari Riuniti Giovanni Rovelli Italy

 


Define an HTML Table

A table in HTML consists of table cells inside rows and columns

Example

A simple HTML table:

<table>
  <tr>
    <th>Company</th>
    <th>Contact</th>
    <th>Country</th>
  </tr>
  <tr>
    <td>Swift Games</td>
    <td>Name</td>
    <td>Germany</td>
  </tr>
  <tr>
    <td>Centro comercial Moctezuma</td>
    <td>Francisco Chang</td>
    <td>Mexico</td>
  </tr>
</table>

Table Cells

Each table cell is defined by a <td> and a </td> tag.

Note:td stands for table data.

Everything between <td> and </td> are the content of the table cell.

Example

<table>
  <tr>
    <td>Emil</td>
    <td>Tobias</td>
    <td>Linus</td>
  </tr>
</table>

Note: table data elements are the data containers of the table.
They can contain all sorts of HTML elements; text, images, lists, other tables, etc.


Table Rows

Each table row starts with a <tr> and end with a </tr> tag.

tr stands for table row.

Example

<table>
  <tr>
    <td>Emil</td>
    <td>Tobias</td>
    <td>Linus</td>
  </tr>
  <tr>
    <td>16</td>
    <td>14</td>
    <td>10</td>
  </tr>
</table>

You can have as many rows as you like in a table, just make sure that the number of cells are the same in each row.

Note: There are times where a row can have less or more cells than another. You will learn about that in a later chapter.


Table Headers

Sometimes you want your cells to be headers, in those cases use the <th> tag instead of the <td> tag:

Example

Let the first row be table headers:

<table>
  <tr>
    <th>Person 1</th>
    <th>Person 2</th>
    <th>Person 3</th>
  </tr>
  <tr>
    <td>Emil</td>
    <td>Tobias</td>
    <td>Linus</td>
  </tr>
  <tr>
    <td>16</td>
    <td>14</td>
    <td>10</td>
  </tr>
</table>
Note: By default, the text in <th> elements are bold and centered, but you can change that with CSS.


HTML Table Borders (#17)

HTML tables can have borders of different styles and shapes.


How To Add a Border

When you add a border to a table, you also add borders around each table cell:

To add a border, use the CSS border property on tableth, and td elements:

Example

table, th, td {
  border: 1px solid black;}

Collapsed Table Borders

To avoid having double borders like in the example above, set the CSS border-collapse property to collapse.

This will make the borders collapse into a single border:

Example

table, th, td {
  border: 1px solid black;
  border-collapse: collapse;}

Style Table Borders

If you set a background color of each cell, and give the border a white color (the same as the document background), you get the impression of an invisible border:

Example

table, th, td {
  border: 1px solid white;
  border-collapse: collapse;}
th, td {
  background-color: #96D4D4;}

Round Table Borders

With the border-radius property, the borders get rounded corners:

Example

table, th, td {
  border: 1px solid black;
  border-radius: 10px;}

Skip the border around the table by leaving out table from the css selector:

Example

th, td {
  border: 1px solid black;
  border-radius: 10px;}

Dotted Table Borders

With the border-style property, you can set the appereance of the border.

The following values are allowed:

  • dotted
  • dashed
  • solid
  • double
  • groove
  • ridge
  • inset
  • outset
  • none
  • hidden

Example

 th, td {
  border-style: dotted;}

Border Color

With the border-color property, you can set the color of the border.

Example

 th, td {
  border-color: #96D4D4;}


HTML Table Sizes (#18)

HTML tables can have different sizes for each column, row or the entire table.



Use the style attribute with the width or height properties to specify the size of a table, row or column.


HTML Table Width

To set the width of a table, add the style attribute to the <table> element:

Example

Set the width of the table to 100%:

<table style="width:100%">
  <tr>
    <th>Firstname</th>
    <th>Lastname</th>
    <th>Age</th>
  </tr>
  <tr>
    <td>John</td>
    <td>Smith</td>
    <td>40</td>
  </tr>
  <tr>
    <td>Eva</td>
    <td>Jackson</td>
    <td>30</td>
  </tr>
</table>

Note: Using a percentage as the size unit for a width means how wide will this element be compared to its parent element, which in this case is the <body> element.


HTML Table Column Width

To set the size of a specific column, add the style attribute on a <th> or <td> element:

Example

Set the width of the first column to 70%:

<table style="width:100%">
  <tr>
    <th style="width:70%">Firstname</th>
    <th>Lastname</th>
    <th>Age</th>
  </tr>
  <tr>
    <td>John</td>
    <td>Smith</td>
    <td>40</td>
  </tr>
  <tr>
    <td>Eva</td>
    <td>Jackson</td>
    <td>30</td>
  </tr>
</table>

HTML Table Row Height

To set the height of a specific row, add the style attribute on a table row element:

Example

Set the height of the second row to 200 pixels:

<table style="width:100%">
  <tr>
    <th>First name</th>
    <th>Last name</th>
    <th>Age</th>
  </tr>
  <tr style="height:200px">
    <td>John</td>
    <td>Smith</td>
    <td>40</td>
  </tr>
  <tr>
    <td>Eva</td>
    <td>Jackson</td>
    <td>30</td>
  </tr>
</table>


HTML Table Headers (#19)

HTML tables can have headers for each column or row, or for many columns/rows.


EMIL TOBIAS LINUS
8:00
9:00
10:00
11:00
12:00
13:00
MON TUE WED THU FRI
8:00
9:00
10:00
11:00
12:00
DECEMBER

HTML Table Headers

Table headers are defined with th elements, each th element represents a table cell.

Example

<table>
  <tr>
    <th>Firstname</th>
    <th>Lastname</th>
    <th>Age</th>
  </tr>
  <tr>
    <td>Jill</td>
    <td>Smith</td>
    <td>50</td>
  </tr>
  <tr>
    <td>Eve</td>
    <td>Jackson</td>
    <td>94</td>
  </tr>
</table>

Vertical Table Headers

To use the first column as table headers, define the first cell in each row as a th element:

Example

<table>
  <tr>
    <th>Firstname</th>
    <td>Jill</td>
    <td>Eve</td>
  </tr>
  <tr>
    <th>Lastname</th>
    <td>Smith</td>
    <td>Jackson</td>
  </tr>
  <tr>
    <th>Age</th>
    <td>94</td>
    <td>50</td>
  </tr>
</table>

Align Table Headers

By default, table headers are bold and centered:

Firstname Lastname Age
Jill Smith 50
Eve Jackson 94

To left-align the table headers, use the CSS text-align property:

Example

th {
  text-align: left;}

Header for Multiple Columns

You can have a header that spans over two or more columns.

Name Age
Jill Smith 50
Eve Jackson 94

To do this, use the colspan attribute on the <th> element:

Example

<table>
  <tr>
    <th colspan="2">Name</th>
    <th>Age</th>
  </tr>
  <tr>
    <td>Jill</td>
    <td>Smith</td>
    <td>50</td>
  </tr>
  <tr>
    <td>Eve</td>
    <td>Jackson</td>
    <td>94</td>
  </tr>
</table>

Table Caption

You can add a caption that serves as a heading for the entire table.

Monthly savings
Month Savings
January $100
February $50

To add a caption to a table, use the <caption> tag:

Example

<table style="width:100%">
  <caption>Monthly savings</caption>
  <tr>
    <th>Month</th>
    <th>Savings</th>
  </tr>
  <tr>
    <td>January</td>
    <td>$100</td>
  </tr>
  <tr>
    <td>February</td>
    <td>$50</td>
  </tr>
</table>

Note: The <caption> tag should be inserted immediately after the <table> ta



HTML Table Padding & Spacing (#20)

HTML tables can adjust the padding inside the cells, and also the space between the cells.


With Padding
hello hello hello
hello hello hello
hello hello hello
With Spacing
hello hello hello
hello hello hello
hello hello hello

HTML Table – Cell Padding

Cell padding is the space between the cell edges and the cell content.

By default the padding is set to 0.

To add padding on table cells, use the CSS padding property:

Example

th, td {
  padding: 15px;}

To add padding only above the content, use the padding-top property.

And the others sides with the padding-bottompadding-left, and padding-right properties:

Example

th, td {
  padding-top: 10px;
  padding-bottom: 20px;
  padding-left: 30px;
  padding-right: 40px;}

HTML Table – Cell Spacing

Cell spacing is the space between each cell.

By default the space is set to 2 pixels.

To change the space between table cells, use the CSS border-spacing property on the table element:

Example

table {
  border-spacing: 30px;}


HTML Table Styling (#21)

Use CSS to make your tables look better.


HTML Table – Zebra Stripes

If you add a background color on every other table row, you will get a nice zebra stripes effect.

1 2 3 4
5 6 7 8
9 10 11 12
13 14 15 16
17 18 19 20

To style every other table row element, use the :nth-child(even) selector like this:

Example

tr:nth-child(even) {
  background-color: #D6EEEE;}

Note: If you use (odd) instead of (even), the styling will occur on row 1,3,5 etc. instead of 2,4,6 etc.


HTML Table – Vertical Zebra Stripes

To make vertical zebra stripes, style every other column, instead of every other row.

1 2 3 4
5 6 7 8
9 10 11 12
13 14 15 16
17 18 19 20

Set the :nth-child(even) for table data elements like this:

Example

td:nth-child(even), th:nth-child(even) {
  background-color: #D6EEEE;}

Note: Put the :nth-child() selector on both th and td elements if you want to have the styling on both headers and regular table cells.


Combine Vertical and Horizontal Zebra Stripes

You can combine the styling from the two examples above and you will have stripes on every other row and every other column.

If you use a transparent color you will get an overlapping effect.

Use an rgba() color to specify the transparency of the color:

Example

tr:nth-child(even) {
  background-color: rgba(150, 212, 212, 0.4);}

th:nth-child(even),td:nth-child(even) {
  background-color: rgba(150, 212, 212, 0.4);}

Horizontal Dividers

First Name Last Name Savings
Peter Griffin $100
Lois Griffin $150
Joe Swanson $300

If you specify borders only at the bottom of each table row, you will have a table with horizontal dividers.

Add the border-bottom property to all tr elements to get horizontal dividers:

Example

tr {
  border-bottom: 1px solid #ddd;}

Hoverable Table

Use the :hover selector on tr to highlight table rows on mouse over:

First Name Last Name Savings
Peter Griffin $100
Lois Griffin $150
Joe Swanson $300

Example

tr:hover {background-color: #D6EEEE;}


HTML Lists (#22)

HTML lists allow web developers to group a set of related items in lists.


Example

An unordered HTML list:

  • Item
  • Item
  • Item
  • Item

An ordered HTML list:

  1. First item
  2. Second item
  3. Third item
  4. Fourth item

Unordered HTML List

An unordered list starts with the <ul> tag. Each list item starts with the <li> tag.

The list items will be marked with bullets (small black circles) by default:

Example

<ul>
  <li>Coffee</li>
  <li>Tea</li>
  <li>Milk</li>
</ul>

Ordered HTML List

An ordered list starts with the <ol> tag. Each list item starts with the <li> tag.

The list items will be marked with numbers by default:

Example

<ol>
  <li>Coffee</li>
  <li>Tea</li>
  <li>Milk</li>
</ol>

HTML Description Lists

HTML also supports description lists.

A description list is a list of terms, with a description of each term.

The <dl> tag defines the description list, the <dt> tag defines the term (name), and the <dd> tag describes each term:

Example

<dl>
  <dt>Coffee</dt>
  <dd>- black hot drink</dd>
  <dt>Milk</dt>
  <dd>- white cold drink</dd>
</dl>


HTML Unordered Lists (#23)

The HTML <ul> tag defines an unordered (bulleted) list.


Unordered HTML List

An unordered list starts with the <ul> tag. Each list item starts with the <li> tag.

The list items will be marked with bullets (small black circles) by default:

Example

<ul>
  <li>Coffee</li>
  <li>Tea</li>
  <li>Milk</li>
</ul>

Unordered HTML List – Choose List Item Marker

The CSS list-style-type property is used to define the style of the list item marker. It can have one of the following values:

Value Description
disc Sets the list item marker to a bullet (default)
circle Sets the list item marker to a circle
square Sets the list item marker to a square
none The list items will not be marked

Example – Disc

<ul style="list-style-type:disc;">
  <li>Coffee</li>
  <li>Tea</li>
  <li>Milk</li>
</ul>

Example – Circle

<ul style="list-style-type:circle;">
  <li>Coffee</li>
  <li>Tea</li>
  <li>Milk</li>
</ul>

Example – Square

<ul style="list-style-type:square;">
  <li>Coffee</li>
  <li>Tea</li>
  <li>Milk</li>
</ul>

Example – None

<ul style="list-style-type:none;">
  <li>Coffee</li>
  <li>Tea</li>
  <li>Milk</li>
</ul>

Nested HTML Lists

Lists can be nested (list inside list):

Example

<ul>
  <li>Coffee</li>
  <li>Tea
    <ul>
      <li>Black tea</li>
      <li>Green tea</li>
    </ul>
  </li>
  <li>Milk</li>
</ul>

Note: A list item (<li>) can contain a new list, and other HTML elements, like images and links, etc.


Horizontal List with CSS

HTML lists can be styled in many different ways with CSS.

One popular way is to style a list horizontally, to create a navigation menu:

Example

<!DOCTYPE html>
<html>
<head>
<style>
ul {
  list-style-type: none;
  margin: 0;
  padding: 0;
  overflow: hidden;
  background-color: #333333;}

li {
  float: left;}

li a {
  display: block;
  color: white;
  text-align: center;
  padding: 16px;
  text-decoration: none;}

li a:hover {
  background-color: #111111;}</style>
</head>
<body>

<ul>
  <li><a href="#home">Home</a></li>
  <li><a href="#news">News</a></li>
  <li><a href="#contact">Contact</a></li>
  <li><a href="#about">About</a></li>
</ul>

</body>
</html>

Chapter Summary

  • Use the HTML <ul> element to define an unordered list
  • Use the CSS list-style-type property to define the list item marker
  • Use the HTML <li> element to define a list item
  • Lists can be nested
  • List items can contain other HTML elements
  • Use the CSS property float:left to display a list horizontally


HTML Ordered Lists (#24)

The HTML <ol> tag defines an ordered list. An ordered list can be numerical or alphabetical.


Ordered HTML List

An ordered list starts with the <ol> tag. Each list item starts with the <li> tag.

The list items will be marked with numbers by default:

Example

<ol>
  <li>Coffee</li>
  <li>Tea</li>
  <li>Milk</li>
</ol>

Ordered HTML List – The Type Attribute

The type attribute of the <ol> tag, defines the type of the list item marker:

Type Description
type=”1″ The list items will be numbered with numbers (default)
type=”A” The list items will be numbered with uppercase letters
type=”a” The list items will be numbered with lowercase letters
type=”I” The list items will be numbered with uppercase roman numbers
type=”i” The list items will be numbered with lowercase roman numbers

Numbers:

<ol type="1">
  <li>Coffee</li>
  <li>Tea</li>
  <li>Milk</li>
</ol>

Uppercase Letters:

<ol type="A">
  <li>Coffee</li>
  <li>Tea</li>
  <li>Milk</li>
</ol>

Lowercase Letters:

<ol type="a">
  <li>Coffee</li>
  <li>Tea</li>
  <li>Milk</li>
</ol>

Uppercase Roman Numbers:

<ol type="I">
  <li>Coffee</li>
  <li>Tea</li>
  <li>Milk</li>
</ol>

Control List Counting

By default, an ordered list will start counting from 1. If you want to start counting from a specified number, you can use the start attribute:

Example

<ol start="50">
  <li>Coffee</li>
  <li>Tea</li>
  <li>Milk</li>
</ol>

Nested HTML Lists

Lists can be nested (list inside list):

Example

<ol>
  <li>Coffee</li>
  <li>Tea
    <ol>
      <li>Black tea</li>
      <li>Green tea</li>
    </ol>
  </li>
  <li>Milk</li>
</ol>

Note: A list item (<li>) can contain a new list, and other HTML elements, like images and links, etc.


Chapter Summary

  • Use the HTML <ol> element to define an ordered list
  • Use the HTML type attribute to define the numbering type
  • Use the HTML <li> element to define a list item
  • Lists can be nested
  • List items can contain other HTML elements


HTML Other Lists (#25)

HTML also supports description lists.


HTML Description Lists

A description list is a list of terms, with a description of each term.

The <dl> tag defines the description list, the <dt> tag defines the term (name), and the <dd> tag describes each term:

Example

<dl>
  <dt>Coffee</dt>
  <dd>- black hot drink</dd>
  <dt>Milk</dt>
  <dd>- white cold drink</dd>
</dl>

Chapter Summary

  • Use the HTML <dl> element to define a description list
  • Use the HTML <dt> element to define the description term
  • Use the HTML <dd> element to describe the term in a description list


HTML Block and Inline Elements (#26)

Every HTML element has a default display value, depending on what type of element it is.

There are two display values: block and inline.


Block-level Elements

A block-level element always starts on a new line, and the browsers automatically add some space (a margin) before and after the element.

A block-level element always takes up the full width available (stretches out to the left and right as far as it can).

Two commonly used block elements are: <p> and <div>.

The <p> element defines a paragraph in an HTML document.

The <div> element defines a division or a section in an HTML document.

The <p> element is a block-level element.

The <div> element is a block-level element.

Example

<p>Hello World</p>
<div>Hello World</div>

Here are the block-level elements in HTML:

<address>

<article>

<aside>

<blockquote>

<canvas>

<dd>

<div>

<dl>

<dt>

<fieldset>

<figcaption>

<figure>

<footer>

<form>

<h1>-<h6>

<header>

<hr>

<li>

<main>

<nav>

<noscript>

<ol>

<p>

<pre>

<section>

<table>

<tfoot>

<ul>

<video>

Inline Elements

An inline element does not start on a new line.

An inline element only takes up as much width as necessary.

This is a <span> element inside a paragraph.

Example

<span>Hello World</span>

ent only takes up as much width as necessary.

This is a <span> element inside a paragraph.

Example

<span>Hello World</span>

Here are the inline elements in HTML:

<a>

<abbr>

<acronym>

<b>

<bdo>

<big>

<br>

<button>

<cite>

<code>

<dfn>

<em>

<i>

<img>

<input>

<kbd>

<label>

<map>

<object>

<output>

<q>

<samp>

<script>

<select>

<small>

<span>

<strong>

<sub>

<sup>

<textarea>

<time>

<tt>

<var>

Note: An inline element cannot contain a block-level element!


The <div> Element

The <div> element is often used as a container for other HTML elements.

The <div> element has no required attributes, but styleclass and id are common.

When used together with CSS, the <div> element can be used to style blocks of content:

Example

<div style="background-color:black;color:white;padding:20px;">
  <h2>London</h2>
  <p>London is the capital city of England. It is the most populous city in the United Kingdom, with a metropolitan area of over 13 million inhabitants.</p>
</div>

The <span> Element

The <span> element is an inline container used to mark up a part of a text, or a part of a document.

The <span> element has no required attributes, but styleclass and id are common.

When used together with CSS, the <span> element can be used to style parts of the text:

Example

<p>My mother has <span style="color:blue;font-weight:bold">blue</span> eyes and my father has <span style="color:darkolivegreen;font-weight:bold">dark green</span> eyes.</p>

Chapter Summary

  • There are two display values: block and inline
  • A block-level element always starts on a new line and takes up the full width available
  • An inline element does not start on a new line and it only takes up as much width as necessary
  • The <div> element is a block-level and is often used as a container for other HTML elements
  • The <span> element is an inline container used to mark up a part of a text, or a part of a document


HTML class Attribute (#27)

The HTML class attribute is used to specify a class for an HTML element.

Multiple HTML elements can share the same class.


Using The class Attribute

The class attribute is often used to point to a class name in a style sheet. It can also be used by a JavaScript to access and manipulate elements with the specific class name.

In the following example we have three <div> elements with a class attribute with the value of “city”. All of the three <div> elements will be styled equally according to the .city style definition in the head section:

Example

<!DOCTYPE html>
<html>
<head>
<style>
.city {
  background-color: tomato;
  color: white;
  border: 2px solid black;
  margin: 20px;
  padding: 20px;}</style>
</head>
<body>

<div class="city">
  <h2>London</h2>
  <p>London is the capital of England.</p>
</div>

<div class="city">
  <h2>Paris</h2>
  <p>Paris is the capital of France.</p>
</div>

<div class="city">
  <h2>Tokyo</h2>
  <p>Tokyo is the capital of Japan.</p>
</div>

</body>
</html>

In the following example we have two <span> elements with a class attribute with the value of “note”. Both <span> elements will be styled equally according to the .note style definition in the head section:

Example

<!DOCTYPE html>
<html>
<head>
<style>
.note {
  font-size: 120%;
  color: red;}</style>
</head>
<body>

<h1>My <span class="note">Important</span> Heading</h1>
<p>This is some <span class="note">important</span> text.</p>

</body>
</html>

Tip: The class attribute can be used on any HTML element.

Note: The class name is case sensitive!


The Syntax For Class

To create a class; write a period (.) character, followed by a class name. Then, define the CSS properties within curly braces {}:

Example

Create a class named “city”:

<!DOCTYPE html>
<html>
<head>
<style>
.city {
  background-color: tomato;
  color: white;
  padding: 10px;}</style>
</head>
<body>

<h2 class="city">London</h2>
<p>London is the capital of England.</p>

<h2 class="city">Paris</h2>
<p>Paris is the capital of France.</p>

<h2 class="city">Tokyo</h2>
<p>Tokyo is the capital of Japan.</p>

</body>
</html>

Multiple Classes

HTML elements can belong to more than one class.

To define multiple classes, separate the class names with a space, e.g. <div class=”city main”>. The element will be styled according to all the classes specified.

In the following example, the first <h2> element belongs to both the city class and also to the main class, and will get the CSS styles from both of the classes:

Example

<h2 class="city main">London</h2>
<h2 class="city">Paris</h2>
<h2 class="city">Tokyo</h2>

Different Elements Can Share Same Class

Different HTML elements can point to the same class name.

In the following example, both <h2> and <p> points to the “city” class and will share the same style:

Example

<h2 class="city">Paris</h2>
<p class="city">Paris is the capital of France</p>

Use of The class Attribute in JavaScript

The class name can also be used by JavaScript to perform certain tasks for specific elements.

JavaScript can access elements with a specific class name with the getElementsByClassName() method:

Example

Click on a button to hide all elements with the class name “city”:

<script>function myFunction() {
var x = document.getElementsByClassName("city");
for (var i = 0; i < x.length; i++) {
    x[i].style.display = "none";
  }
}
</script>

Don’t worry if you don’t understand the code in the example above.

You will learn more about JavaScript in our HTML JavaScript chapter, or you can study our JavaScript Tutorial.


Chapter Summary

  • The HTML class attribute specifies one or more class names for an element
  • Classes are used by CSS and JavaScript to select and access specific elements
  • The class attribute can be used on any HTML element
  • The class name is case sensitive
  • Different HTML elements can point to the same class name
  • JavaScript can access elements with a specific class name with the getElementsByClassName() method


HTML id Attribute (#28)

The HTML id attribute is used to specify a unique id for an HTML element.

You cannot have more than one element with the same id in an HTML document.


Using The id Attribute

The id attribute specifies a unique id for an HTML element. The value of the id attribute must be unique within the HTML document.

The id attribute is used to point to a specific style declaration in a style sheet. It is also used by JavaScript to access and manipulate the element with the specific id.

The syntax for id is: write a hash character (#), followed by an id name. Then, define the CSS properties within curly braces {}.

In the following example we have an <h1> element that points to the id name “myHeader”. This <h1> element will be styled according to the #myHeader style definition in the head section:

Example

<!DOCTYPE html>
<html>
<head>
<style>
#myHeader {
  background-color: lightblue;
  color: black;
  padding: 40px;
  text-align: center;}</style>
</head>
<body>

<h1 id="myHeader">My Header</h1>

</body>
</html>

Note: The id name is case sensitive!

Note: The id name must contain at least one character, cannot start with a number, and must not contain whitespaces (spaces, tabs, etc.).


Difference Between Class and ID

A class name can be used by multiple HTML elements, while an id name must only be used by one HTML element within the page:

Example

<style>/* Style the element with the id "myHeader" */#myHeader{
  background-color: lightblue;
  color: black;
  padding: 40px;
  text-align: center;}

/* Style all elements with the class name "city" */.city {
  background-color: tomato;
  color: white;
  padding: 10px;}</style>

<!-- An element with a unique id -->
<h1 id="myHeader">My Cities</h1>

<!-- Multiple elements with same class -->
<h2 class="city">London</h2>
<p>London is the capital of England.</p>

<h2 class="city">Paris</h2>
<p>Paris is the capital of France.</p>

<h2 class="city">Tokyo</h2>
<p>Tokyo is the capital of Japan.</p>

HTML Bookmarks with ID and Links

HTML bookmarks are used to allow readers to jump to specific parts of a webpage.

Bookmarks can be useful if your page is very long.

To use a bookmark, you must first create it, and then add a link to it.

Then, when the link is clicked, the page will scroll to the location with the bookmark.

Example

First, create a bookmark with the id attribute:

<h2 id="C4">Chapter 4</h2>

Then, add a link to the bookmark

Example

<a href="#C4">Jump to Chapter 4</a>

Or, add a link to the bookmark

<a href="html_demo.html#C4">Jump to Chapter 4</a>

Using The id Attribute in JavaScript

The id attribute can also be used by JavaScript to perform some tasks for that specific element.

JavaScript can access an element with a specific id with the getElementById() method:

Example

Use the id attribute to manipulate text with JavaScript:

<script>function displayResult() {
  document.getElementById("myHeader").innerHTML = "Have a nice day!";
}
</script>

Chapter Summary

  • The id attribute is used to specify a unique id for an HTML element
  • The value of the id attribute must be unique within the HTML document
  • The id attribute is used by CSS and JavaScript to style/select a specific element
  • The value of the id attribute is case sensitive
  • The id attribute is also used to create HTML bookmarks
  • JavaScript can access an element with a specific id with the getElementById() method


HTML Iframes (#29)

An HTML iframe is used to display a web page within a web page.


HTML Iframe Syntax

The HTML <iframe> tag specifies an inline frame.

An inline frame is used to embed another document within the current HTML document.

Syntax

<iframe src="url" title="description"></iframe>

Tip: It is a good practice to always include a title attribute for the <iframe>. This is used by screen readers to read out what the content of the iframe is.


Iframe – Set Height and Width

Use the height and width attributes to specify the size of the iframe.

The height and width are specified in pixels by default:

Example

<iframe src="demo_iframe.htm" height="200" width="300" title="Iframe Example"></iframe>

Or you can add the style attribute and use the CSS height and width properties:

Example

<iframe src="demo_iframe.htm" style="height:200px;width:300px;" title="Iframe Example"></iframe>

Iframe – Remove the Border

By default, an iframe has a border around it.

To remove the border, add the style attribute and use the CSS border property:

Example

<iframe src="demo_iframe.htm" style="border:none;" title="Iframe Example"></iframe>

With CSS, you can also change the size, style and color of the iframe’s border:

Example

<iframe src="demo_iframe.htm" style="border:2px solid red;" title="Iframe Example"></iframe>

Iframe – Target for a Link

An iframe can be used as the target frame for a link.

The target attribute of the link must refer to the name attribute of the iframe:

Example

<iframe src="demo_iframe.htm" name="iframe_a" title="Iframe Example"></iframe>

<p><a href="https://www.apostube.com" target="iframe_a">apostube.com</a></p>

Chapter Summary

  • The HTML <iframe> tag specifies an inline frame
  • The src attribute defines the URL of the page to embed
  • Always include a title attribute (for screen readers)
  • The height and width attributes specifies the size of the iframe
  • Use border:none; to remove the border around the iframe


HTML JavaScript (#30)

JavaScript makes HTML pages more dynamic and interactive.


Example

My First JavaScript


The HTML <script> Tag

The HTML <script> tag is used to define a client-side script (JavaScript).

The <script> element either contains script statements, or it points to an external script file through the src attribute.

Common uses for JavaScript are image manipulation, form validation, and dynamic changes of content.

To select an HTML element, JavaScript most often uses the document.getElementById() method.

This JavaScript example writes “Hello JavaScript!” into an HTML element with id=”demo”:

Example

<script>
document.getElementById("demo").innerHTML = "Hello JavaScript!";
</script>

Tip: You can learn much more about JavaScript in our JavaScript Tutorial.


A Taste of JavaScript

Here are some examples of what JavaScript can do:

Example

JavaScript can change content:

document.getElementById("demo").innerHTML = "Hello JavaScript!";

Example

JavaScript can change styles:

document.getElementById("demo").style.fontSize = "25px";
document.getElementById("demo").style.color = "red";
document.getElementById("demo").style.backgroundColor = "yellow";

Example

JavaScript can change attributes:

document.getElementById("image").src = "picture.gif";

The HTML <noscript> Tag

The HTML <noscript> tag defines an alternate content to be displayed to users that have disabled scripts in their browser or have a browser that doesn’t support scripts:

Example

<script>
document.getElementById("demo").innerHTML = "Hello JavaScript!";
</script>
<noscript>Sorry, your browser does not support JavaScript!</noscript>


HTML File Paths (#31)

A file path describes the location of a file in a web site’s folder structure.


File Path Examples

Path Description
<img src=”picture.jpg”> The “picture.jpg” file is located in the same folder as the current page
<img src=”images/picture.jpg”> The “picture.jpg” file is located in the images folder in the current folder
<img src=”/images/picture.jpg”> The “picture.jpg” file is located in the images folder at the root of the current web
<img src=”../picture.jpg”> The “picture.jpg” file is located in the folder one level up from the current folder

HTML File Paths

A file path describes the location of a file in a web site’s folder structure.

File paths are used when linking to external files, like:

  • Web pages
  • Images
  • Style sheets
  • JavaScripts

Absolute File Paths

An absolute file path is the full URL to a file:

Example

<img src="https://www.apostube.com/images/picture.jpg" alt="Mountain">

Relative File Paths

A relative file path points to a file relative to the current page.

In the following example, the file path points to a file in the images folder located at the root of the current web:

Example

<img src="/images/picture.jpg" alt="Mountain">

In the following example, the file path points to a file in the images folder located in the current folder:

Example

<img src="images/picture.jpg" alt="Mountain">

In the following example, the file path points to a file in the images folder located in the folder one level up from the current folder:

Example

<img src="../images/picture.jpg" alt="Mountain">


HTML – The Head Element (#32)

The HTML <head> element is a container for the following elements: <title><style><meta><link><script>, and <base>.


The HTML <head> Element

The <head> element is a container for metadata (data about data) and is placed between the <html> tag and the <body> tag.

HTML metadata is data about the HTML document. Metadata is not displayed.

Metadata typically define the document title, character set, styles, scripts, and other meta information.


The HTML <title> Element

The <title> element defines the title of the document. The title must be text-only, and it is shown in the browser’s title bar or in the page’s tab.

The <title> element is required in HTML documents!

The contents of a page title is very important for search engine optimization (SEO)! The page title is used by search engine algorithms to decide the order when listing pages in search results.

The <title> element:

  • defines a title in the browser toolbar
  • provides a title for the page when it is added to favorites
  • displays a title for the page in search engine-results

So, try to make the title as accurate and meaningful as possible!

A simple HTML document:

Example

<!DOCTYPE html>
<html>
<head>
  <title>A Meaningful Page Title</title>
</head>
<body>

The content of the document......

</body>
</html>

The HTML <style> Element

The <style> element is used to define style information for a single HTML page:

Example

<style>
  body {background-color: powderblue;}
  h1 {color: red;}
  p {color: blue;}</style>

The HTML <link> Element

The <link> element defines the relationship between the current document and an external resource.

The <link> tag is most often used to link to external style sheets:

Example

<link rel="stylesheet" href="mystyle.css">

The HTML <meta> Element

The <meta> element is typically used to specify the character set, page description, keywords, author of the document, and viewport settings.

The metadata will not be displayed on the page, but are used by browsers (how to display content or reload page), by search engines (keywords), and other web services.

Examples

Define the character set used:

<meta charset="UTF-8">

Define keywords for search engines:

<meta name="keywords" content="HTML, CSS, JavaScript">

Define a description of your web page:

<meta name="description" content="Free Web tutorials">

Define the author of a page:

<meta name="author" content="John Doe">

Refresh document every 30 seconds:

<meta http-equiv="refresh" content="30">

Setting the viewport to make your website look good on all devices:

<meta name="viewport" content="width=device-width, initial-scale=1.0">

Example of <meta> tags:

Example

<meta charset="UTF-8">
<meta name="description" content="Free Web tutorials">
<meta name="keywords" content="HTML, CSS, JavaScript">
<meta name="author" content="John Doe">

Setting The Viewport

The viewport is the user’s visible area of a web page. It varies with the device – it will be smaller on a mobile phone than on a computer screen.

You should include the following <meta> element in all your web pages:

<meta name="viewport" content="width=device-width, initial-scale=1.0">

This gives the browser instructions on how to control the page’s dimensions and scaling.

The width=device-width part sets the width of the page to follow the screen-width of the device (which will vary depending on the device).

The initial-scale=1.0 part sets the initial zoom level when the page is first loaded by the browser.

Here is an example of a web page without the viewport meta tag, and the same web page with the viewport meta tag:

Tip: If you are browsing this page with a phone or a tablet, you can click on the two links below to see the difference.

Without the viewport meta tag

With the viewport meta tag


The HTML <script> Element

The <script> element is used to define client-side JavaScripts.

The following JavaScript writes “Hello JavaScript!” into an HTML element with id=”demo”:

Example

<script>function myFunction() {
document.getElementById("demo").innerHTML = "Hello JavaScript!";
}
</script>

Tip: To learn all about JavaScript, visit our JavaScript Tutorial.


The HTML <base> Element

The <base> element specifies the base URL and/or target for all relative URLs in a page.

The <base> tag must have either an href or a target attribute present, or both.

There can only be one single <base> element in a document!

Example

Specify a default URL and a default target for all links on a page:

<head>
<base href="https://www.apostube.com/" target="_blank">
</head>

<body>
<img src="images/stickman.gif" width="24" height="39" alt="Stickman">
<a href="tags/tag_base.asp">HTML base Tag</a>
</body>

Chapter Summary

  • The <head> element is a container for metadata (data about data)
  • The <head> element is placed between the <html> tag and the <body> tag
  • The <title> element is required and it defines the title of the document
  • The <style> element is used to define style information for a single document
  • The <link> tag is most often used to link to external style sheets
  • The <meta> element is typically used to specify the character set, page description, keywords, author of the document, and viewport settings
  • The <script> element is used to define client-side JavaScripts
  • The <base> element specifies the base URL and/or target for all relative URLs in a page


HTML Layout Elements and Techniques (#33)

Websites often display content in multiple columns (like a magazine or a newspaper).

HTML Layout Elements

HTML has several semantic elements that define the different parts of a web page:

HTML5 Semantic Elements
  • <header> – Defines a header for a document or a section
  • <nav> – Defines a set of navigation links
  • <section> – Defines a section in a document
  • <article> – Defines an independent, self-contained content
  • <aside> – Defines content aside from the content (like a sidebar)
  • <footer> – Defines a footer for a document or a section
  • <details> – Defines additional details that the user can open and close on demand
  • <summary> – Defines a heading for the <details> element

 


HTML Layout Techniques

There are four different techniques to create multicolumn layouts. Each technique has its pros and cons:

  • CSS framework
  • CSS float property
  • CSS flexbox
  • CSS grid

CSS Frameworks

If you want to create your layout fast, you can use a CSS framework

CSS Float Layout

It is common to do entire web layouts using the CSS float property. Float is easy to learn – you just need to remember how the float and clear properties work.



HTML Responsive Web Design (#34)

Responsive web design is about creating web pages that look good on all devices!

A responsive web design will automatically adjust for different screen sizes and viewports.


What is Responsive Web Design?

Responsive Web Design is about using HTML and CSS to automatically resize, hide, shrink, or enlarge, a website, to make it look good on all devices (desktops, tablets, and phones):


Setting The Viewport

To create a responsive website, add the following <meta> tag to all your web pages:

Example

<meta name="viewport" content="width=device-width, initial-scale=1.0">

This will set the viewport of your page, which will give the browser instructions on how to control the page’s dimensions and scaling.

Here is an example of a web page without the viewport meta tag, and the same web page with the viewport meta tag:

Without the viewport meta tag:
With the viewport meta tag:

Tip: If you are browsing this page on a phone or a tablet, you can click on the two links above to see the difference.


Responsive Images

Responsive images are images that scale nicely to fit any browser size.

Using the width Property

If the CSS width property is set to 100%, the image will be responsive and scale up and down:

Example

<img src="img_girl.jpg"style="width:100%;">

Notice that in the example above, the image can be scaled up to be larger than its original size. A better solution, in many cases, will be to use the max-width property instead.


Using the max-width Property

If the max-width property is set to 100%, the image will scale down if it has to, but never scale up to be larger than its original size:

Example

<img src="img_girl.jpg" style="max-width:100%;height:auto;">

Show Different Images Depending on Browser Width

The HTML <picture> element allows you to define different images for different browser window sizes.

Resize the browser window to see how the image below change depending on the width:

Flowers

Example

<picture>
  <source srcset="img_smallflower.jpg" media="(max-width: 600px)">
  <source srcset="img_flowers.jpg" media="(max-width: 1500px)">
  <source srcset="flowers.jpg">
  <img src="img_smallflower.jpg" alt="Flowers">
</picture>

Responsive Text Size

The text size can be set with a “vw” unit, which means the “viewport width”.

That way the text size will follow the size of the browser window:


Hello World

Resize the browser window to see how the text size scales.

Example

<h1 style="font-size:10vw">Hello World</h1>

Media Queries

In addition to resize text and images, it is also common to use media queries in responsive web pages.

With media queries you can define completely different styles for different browser sizes.

Example: resize the browser window to see that the three div elements below will display horizontally on large screens and stacked vertically on small screens:

Example

<style>
.left, .right {
  float: left;
  width: 20%; /* The width is 20%, by default */}

.main {
  float: left;
  width: 60%; /* The width is 60%, by default */}

/* Use a media query to add a breakpoint at 800px: */
@media screen and (max-width: 800px) {
  .left, .main, .right {
    width: 100%; /* The width is 100%, when the viewport is 800px or smaller */}
}</style>

apostube.codes

Another popular CSS framework is apostube. apostube.com uses HTML, CSS and jQuery to make responsive web pages.

Example

<!DOCTYPE html>
<html lang="en">
<head>
<title>Apostube Example</title>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<link rel="stylesheet" href="https://apostube.com/category/codes/css/apostube.min.css">
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.5.1/jquery.min.js"></script>
<script src="https://apostube.com/category/codes/js/apostube.min.js"></script>
</head>
<body>

<div class="container">
  <div class="jumbotron">
    <h1>My First Web Page</h1>
  </div>
  <div class="row">
    <div class="col-sm-4">
      ...
    </div>
    <div class="col-sm-4">
      ...
    </div>
    <div class="col-sm-4">
    ...
    </div>
  </div>
</div>

</body>
</html>


HTML Computer Code Elements (#35)

HTML contains several elements for defining user input and computer code.


Example

<code>
x = 5;
y = 6;
z = x + y;
</code>

HTML <kbd> For Keyboard Input

The HTML <kbd> element is used to define keyboard input. The content inside is displayed in the browser’s default monospace font.

Example

Define some text as keyboard input in a document:

<p>Save the document by pressing <kbd>Ctrl + S</kbd></p>

Result:

Save the document by pressing Ctrl + S

HTML <samp> For Program Output

The HTML <samp> element is used to define sample output from a computer program. The content inside is displayed in the browser’s default monospace font.

Example

Define some text as sample output from a computer program in a document:

<p>Message from my computer:</p>
<p><samp>File not found.<br>Press F1 to continue</samp></p>

Result:

Message from my computer:File not found.
Press F1 to continue

HTML <code> For Computer Code

The HTML <code> element  is used to define a piece of computer code. The content inside is displayed in the browser’s default monospace font.

Example

Define some text as computer code in a document:

<code>
x = 5;
y = 6;
z = x + y;
</code>

Result:

x = 5; y = 6; z = x + y;

Notice that the <code> element does not preserve extra whitespace and line-breaks.

To fix this, you can put the <code> element inside a <pre> element:

Example

<pre>
<code>
x = 5;
y = 6;
z = x + y;
</code>
</pre>

Result:

x = 5;
y = 6;
z = x + y;

HTML <var> For Variables

The HTML <var> element  is used to define a variable in programming or in a mathematical expression. The content inside is typically displayed in italic.

Example

Define some text as variables in a document:

<p>The area of a triangle is: 1/2 x <var>b</var> x <var>h</var>, where <var>b</var> is the base, and <var>h</var> is the vertical height.</p>

Result:

The area of a triangle is: 1/2 x b x h, where b is the base, and h is the vertical height.

Chapter Summary

  • The <kbd> element defines keyboard input
  • The <samp> element defines sample output from a computer program
  • The <code> element defines a piece of computer code
  • The <var> element defines a variable in programming or in a mathematical expression
  • The <pre> element defines preformatted text


HTML Semantic Elements (#36)

Semantic elements = elements with a meaning.


What are Semantic Elements?

A semantic element clearly describes its meaning to both the browser and the developer.

Examples of non-semantic elements: <div> and <span> – Tells nothing about its content.

Examples of semantic elements: <form><table>, and <article> – Clearly defines its content.


Semantic Elements in HTML

Many web sites contain HTML code like: <div id=”nav”> <div class=”header”> <div id=”footer”> to indicate navigation, header, and footer.

In HTML there are some semantic elements that can be used to define different parts of a web page:

  • <article>
  • <aside>
  • <details>
  • <figcaption>
  • <figure>
  • <footer>
  • <header>
  • <main>
  • <mark>
  • <nav>
  • <section>
  • <summary>
  • <time>
HTML Semantic Elements

 


HTML <section> Element

The <section> element defines a section in a document.

According to W3C’s HTML documentation: “A section is a thematic grouping of content, typically with a heading.”

Examples of where a <section> element can be used:

  • Chapters
  • Introduction
  • News items
  • Contact information

A web page could normally be split into sections for introduction, content, and contact information.

Example

Two sections in a document:

<section>
<h1>WWF</h1>
<p>The World Wide Fund for Nature (WWF) is an international organization working on issues regarding the conservation, research and restoration of the environment, formerly named the World Wildlife Fund. WWF was founded in 1961.</p>
</section>

<section>
<h1>WWF's Panda symbol</h1>
<p>The Panda has become the symbol of WWF. The well-known panda logo of WWF originated from a panda named Chi Chi that was transferred from the Beijing Zoo to the London Zoo in the same year of the establishment of WWF.</p>
</section>

HTML <article> Element

The <article> element specifies independent, self-contained content.

An article should make sense on its own, and it should be possible to distribute it independently from the rest of the web site.

Examples of where the <article> element can be used:

  • Forum posts
  • Blog posts
  • User comments
  • Product cards
  • Newspaper articles

Example

Three articles with independent, self-contained content:

<article>
<h2>Google Chrome</h2>
<p>Google Chrome is a web browser developed by Google, released in 2008. Chrome is the world's most popular web browser today!</p>
</article>

<article>
<h2>Mozilla Firefox</h2>
<p>Mozilla Firefox is an open-source web browser developed by Mozilla. Firefox has been the second most popular web browser since January, 2018.</p>
</article>

<article>
<h2>Microsoft Edge</h2>
<p>Microsoft Edge is a web browser developed by Microsoft, released in 2015. Microsoft Edge replaced Internet Explorer.</p>
</article>

Example 2

Use CSS to style the <article> element:

<html>
<head>
<style>
.all-browsers {
  margin: 0;
  padding: 5px;
  background-color: lightgray;}

.all-browsers > h1, .browser {
  margin: 10px;
  padding: 5px;}

.browser {
  background: white;}

.browser > h2, p {
  margin: 4px;
  font-size: 90%;}</style>
</head>
<body>

<article class="all-browsers">
  <h1>Most Popular Browsers</h1>
  <article class="browser">
    <h2>Google Chrome</h2>
    <p>Google Chrome is a web browser developed by Google, released in 2008. Chrome is the world's most popular web browser today!</p>
  </article>
  <article class="browser">
    <h2>Mozilla Firefox</h2>
    <p>Mozilla Firefox is an open-source web browser developed by Mozilla. Firefox has been the second most popular web browser since January, 2018.</p>
  </article>
  <article class="browser">
    <h2>Microsoft Edge</h2>
    <p>Microsoft Edge is a web browser developed by Microsoft, released in 2015. Microsoft Edge replaced Internet Explorer.</p>
  </article>
</article>

</body>
</html>

Nesting <article> in <section> or Vice Versa?

The <article> element specifies independent, self-contained content.

The <section> element defines section in a document.

Can we use the definitions to decide how to nest those elements? No, we cannot!

So, you will find HTML pages with <section> elements containing <article> elements, and <article> elements containing <section> elements.


HTML <header> Element

The <header> element represents a container for introductory content or a set of navigational links.

<header> element typically contains:

  • one or more heading elements (<h1> – <h6>)
  • logo or icon
  • authorship information

Note: You can have several <header> elements in one HTML document. However, <header> cannot be placed within a <footer><address> or another <header> element.

Example

A header for an <article>:

<article>
  <header>
    <h1>What Does WWF Do?</h1>
    <p>WWF's mission:</p>
  </header>
  <p>WWF's mission is to stop the degradation of our planet's natural environment,
  and build a future in which humans live in harmony with nature.</p>
</article>

HTML <footer> Element

The <footer> element defines a footer for a document or section.

<footer> element typically contains:

  • authorship information
  • copyright information
  • contact information
  • sitemap
  • back to top links
  • related documents

You can have several <footer> elements in one document.

Example

A footer section in a document:

<footer>
  <p>Author: Hege Refsnes</p>
  <p><a href="mailto:hege@example.com">hege@example.com</a></p>
</footer>

HTML <nav> Element

The <nav> element defines a set of navigation links.

Notice that NOT all links of a document should be inside a <nav> element. The <nav> element is intended only for major block of navigation links.

Browsers, such as screen readers for disabled users, can use this element to determine whether to omit the initial rendering of this content.

Example

A set of navigation links:

<nav>
  <a href="/html/">HTML</a> |
  <a href="/css/">CSS</a> |
  <a href="/js/">JavaScript</a> |
  <a href="/jquery/">jQuery</a>
</nav>

HTML <aside> Element

The <aside> element defines some content aside from the content it is placed in (like a sidebar).

The <aside> content should be indirectly related to the surrounding content.

Example 1

Display some content aside from the content it is placed in:

<p>My family and I visited The Epcot center this summer. The weather was nice, and Epcot was amazing! I had a great summer together with my family!</p>

<aside>
<h4>Epcot Center</h4>
<p>Epcot is a theme park at Walt Disney World Resort featuring exciting attractions, international pavilions, award-winning fireworks and seasonal special events.</p>
</aside>

Example 2

Use CSS to style the <aside> element:

<html>
<head>
<style>
aside {
  width: 30%;
  padding-left: 15px;
  margin-left: 15px;
  float: right;
  font-style: italic;
  background-color: lightgray;}</style>
</head>
<body>

<p>My family and I visited The Epcot center this summer. The weather was nice, and Epcot was amazing! I had a great summer together with my family!</p>

<aside>
<p>The Epcot center is a theme park at Walt Disney World Resort featuring exciting attractions, international pavilions, award-winning fireworks and seasonal special events.</p>
</aside>

<p>My family and I visited The Epcot center this summer. The weather was nice, and Epcot was amazing! I had a great summer together with my family!</p>
<p>My family and I visited The Epcot center this summer. The weather was nice, and Epcot was amazing! I had a great summer together with my family!</p>

</body>
</html>

HTML <figure> and <figcaption> Elements

The <figure> tag specifies self-contained content, like illustrations, diagrams, photos, code listings, etc.

The <figcaption> tag defines a caption for a <figure> element. The <figcaption> element can be placed as the first or as the last child of a <figure> element.

The <img> element defines the actual image/illustration.

Example

<figure>
  <img src="pic_trulli.jpg" alt="Trulli">
  <figcaption>Fig1. - Trulli, Puglia, Italy.</figcaption>
</figure>

Why Semantic Elements?

A semantic Web allows data to be shared and reused across applications, enterprises, and communities.



HTML Style Guide (#37)

A consistent, clean, and tidy HTML code makes it easier for others to read and understand your code.

Here are some guidelines and tips for creating good HTML code.


Always Declare Document Type

Always declare the document type as the first line in your document.

The correct document type for HTML is:

<!DOCTYPE html>

Use Lowercase Element Names

HTML allows mixing uppercase and lowercase letters in element names.

However, we recommend using lowercase element names, because:

  • Mixing uppercase and lowercase names looks bad
  • Developers normally use lowercase names
  • Lowercase looks cleaner
  • Lowercase is easier to write

Good:

<body>
<p>This is a paragraph.</p>
</body>

Bad:

<BODY>
<P>This is a paragraph.</P>
</BODY>

Close All HTML Elements

In HTML, you do not have to close all elements (for example the <p> element).

However, we strongly recommend closing all HTML elements, like this:

Good:

<section>
  <p>This is a paragraph.</p>
  <p>This is a paragraph.</p>
</section>

Bad:

<section>
  <p>This is a paragraph.
  <p>This is a paragraph.
</section>

Use Lowercase Attribute Names

HTML allows mixing uppercase and lowercase letters in attribute names.

However, we recommend using lowercase attribute names, because:

  • Mixing uppercase and lowercase names looks bad
  • Developers normally use lowercase names
  • Lowercase look cleaner
  • Lowercase are easier to write

Good:

<a href="https://apostube.com/category/html/">Visit our HTML tutorial</a>

Bad:

<a HREF="https://apostube.com/category/html/">Visit our HTML tutorial</a>

Always Quote Attribute Values

HTML allows attribute values without quotes.

However, we recommend quoting attribute values, because:

  • Developers normally quote attribute values
  • Quoted values are easier to read
  • You MUST use quotes if the value contains spaces

Good:

<table class="striped">

Bad:

<table class=striped>

Very bad:

This will not work, because the value contains spaces:

<table class=table striped>

Always Specify alt, width, and height for Images

Always specify the alt attribute for images. This attribute is important if the image for some reason cannot be displayed.

Also, always define the width and height of images. This reduces flickering, because the browser can reserve space for the image before loading.

Good:

<img src="html5.gif" alt="HTML5" style="width:128px;height:128px">

Bad:

<img src="html5.gif">

Spaces and Equal Signs

HTML allows spaces around equal signs. But space-less is easier to read and groups entities better together.

Good:

<link rel="stylesheet" href="styles.css">

Bad:

<link rel = "stylesheet" href = "styles.css">

Avoid Long Code Lines

When using an HTML editor, it is NOT convenient to scroll right and left to read the HTML code.

Try to avoid too long code lines.


Blank Lines and Indentation

Do not add blank lines, spaces, or indentations without a reason.

For readability, add blank lines to separate large or logical code blocks.

For readability, add two spaces of indentation. Do not use the tab key.

Good:

<body>

<h1>Famous Cities</h1>

<h2>Tokyo</h2>
<p>Tokyo is the capital of Japan, the center of the Greater Tokyo Area, and the most populous metropolitan area in the world.</p>

<h2>London</h2>
<p>London is the capital city of England. It is the most populous city in the United Kingdom.</p>

<h2>Paris</h2>
<p>Paris is the capital of France. The Paris area is one of the largest population centers in Europe.</p>

</body>

Bad:

<body>
<h1>Famous Cities</h1>
<h2>Tokyo</h2><p>Tokyo is the capital of Japan, the center of the Greater Tokyo Area, and the most populous metropolitan area in the world.</p>
<h2>London</h2><p>London is the capital city of England. It is the most populous city in the United Kingdom.</p>
<h2>Paris</h2><p>Paris is the capital of France. The Paris area is one of the largest population centers in Europe.</p>
</body>

Good Table Example:

<table>
  <tr>
    <th>Name</th>
    <th>Description</th>
  </tr>
  <tr>
    <td>A</td>
    <td>Description of A</td>
  </tr>
  <tr>
    <td>B</td>
    <td>Description of B</td>
  </tr>
</table>

Good List Example:

<ul>
  <li>London</li>
  <li>Paris</li>
  <li>Tokyo</li>
</ul>

Never Skip the <title> Element

The <title> element is required in HTML.

The contents of a page title is very important for search engine optimization (SEO)! The page title is used by search engine algorithms to decide the order when listing pages in search results.

The <title> element:

  • defines a title in the browser toolbar
  • provides a title for the page when it is added to favorites
  • displays a title for the page in search-engine results

So, try to make the title as accurate and meaningful as possible:

<title>HTML Style Guide and Coding Conventions</title>

Omitting <html> and <body>?

An HTML page will validate without the <html> and <body> tags:

Example

<!DOCTYPE html>
<head>
  <title>Page Title</title>
</head>

<h1>This is a heading</h1>
<p>This is a paragraph.</p>

However, we strongly recommend to always add the <html> and <body> tags!

Omitting <body> can produce errors in older browsers.

Omitting <html> and <body> can also crash DOM and XML software.


Omitting <head>?

The HTML <head> tag can also be omitted.

Browsers will add all elements before <body>, to a default <head> element.

Example

<!DOCTYPE html>
<html>
<title>Page Title</title>
<body>

<h1>This is a heading</h1>
<p>This is a paragraph.</p>

</body>
</html>

However, we recommend using the <head> tag.


Close Empty HTML Elements?

In HTML, it is optional to close empty elements.

Allowed:

<meta charset="utf-8">

Also Allowed:

<meta charset="utf-8" />

If you expect XML/XHTML software to access your page, keep the closing slash (/), because it is required in XML and XHTML.


Add the lang Attribute

You should always include the lang attribute inside the <html> tag, to declare the language of the Web page. This is meant to assist search engines and browsers.

Example

<!DOCTYPE html>
<html lang="en-us">
<head>
  <title>Page Title</title>
</head>
<body>

<h1>This is a heading</h1>
<p>This is a paragraph.</p>

</body>
</html>

Meta Data

To ensure proper interpretation and correct search engine indexing, both the language and the character encoding <meta charset="charset"> should be defined as early as possible in an HTML document:

<!DOCTYPE html>
<html lang="en-us">
<head>
  <meta charset="UTF-8">
  <title>Page Title</title>
</head>

Setting The Viewport

The viewport is the user’s visible area of a web page. It varies with the device – it will be smaller on a mobile phone than on a computer screen.

You should include the following <meta> element in all your web pages:

<meta name=”viewport” content=”width=device-width, initial-scale=1.0″>

This gives the browser instructions on how to control the page’s dimensions and scaling.

The width=device-width part sets the width of the page to follow the screen-width of the device (which will vary depending on the device).

The initial-scale=1.0 part sets the initial zoom level when the page is first loaded by the browser.


HTML Comments

Short comments should be written on one line, like this:

<!-- This is a comment -->

Comments that spans more than one line, should be written like this:

<!--
  This is a long comment example. This is a long comment example.
  This is a long comment example. This is a long comment example.
-->

Long comments are easier to observe if they are indented with two spaces.


Using Style Sheets

Use simple syntax for linking to style sheets (the type attribute is not necessary):

<link rel="stylesheet" href="styles.css">
Short CSS rules can be written compressed, like this:

p.intro {font-family:Verdana;font-size:16em;}
Long CSS rules should be written over multiple lines:
body {
  background-color: lightgrey;
  font-family: "Arial Black", Helvetica, sans-serif;
  font-size: 16em;
  color: black;}
  • Place the opening bracket on the same line as the selector
  • Use one space before the opening bracket
  • Use two spaces of indentation
  • Use semicolon after each property-value pair, including the last
  • Only use quotes around values if the value contains spaces
  • Place the closing bracket on a new line, without leading spaces

Loading JavaScript in HTML

Use simple syntax for loading external scripts (the type attribute is not necessary):

<script src=”myscript.js”>

Accessing HTML Elements with JavaScript

Using “untidy” HTML code can result in JavaScript errors.

These two JavaScript statements will produce different results:

Example

getElementById("Demo").innerHTML = "Hello";

getElementById("demo").innerHTML = "Hello";

Use Lower Case File Names

Some web servers (Apache, Unix) are case sensitive about file names: “london.jpg” cannot be accessed as “London.jpg”.

Other web servers (Microsoft, IIS) are not case sensitive: “london.jpg” can be accessed as “London.jpg”.

If you use a mix of uppercase and lowercase, you have to be aware of this.

If you move from a case-insensitive to a case-sensitive server, even small errors will break your web!

To avoid these problems, always use lowercase file names!


File Extensions

HTML files should have a .html extension (.htm is allowed).

CSS files should have a .css extension.

JavaScript files should have a .js extension.



HTML Entities (#38)

Reserved characters in HTML must be replaced with character entities.


HTML Entities

Some characters are reserved in HTML.

If you use the less than (<) or greater than (>) signs in your text, the browser might mix them with tags.

Character entities are used to display reserved characters in HTML.

A character entity looks like this:

&entity_name;

OR

&#entity_number;

To display a less than sign (<) we must write: &lt; or &#60;


Non-breaking Space

A commonly used entity in HTML is the non-breaking space: &nbsp;

A non-breaking space is a space that will not break into a new line.

Two words separated by a non-breaking space will stick together (not break into a new line). This is handy when breaking the words might be disruptive.

Examples:

  • § 10
  • 10 km/h
  • 10 PM

Another common use of the non-breaking space is to prevent browsers from truncating spaces in HTML pages.

If you write 10 spaces in your text, the browser will remove 9 of them. To add real spaces to your text, you can use the &nbsp; character entity.


Combining Diacritical Marks

A diacritical mark is a “glyph” added to a letter.

Some diacritical marks, like grave (  ̀) and acute (  ́) are called accents.

Diacritical marks can appear both above and below a letter, inside a letter, and between two letters.

Diacritical marks can be used in combination with alphanumeric characters to produce a character that is not present in the character set (encoding) used in the page.



HTML Symbols (#39)

Symbols that are not present on your keyboard can also be added by using entities.


HTML Symbol Entities

HTML entities were described in the previous chapter.

Many mathematical, technical, and currency symbols, are not present on a normal keyboard.

To add such symbols to an HTML page, you can use the entity name or the entity number (a decimal or a hexadecimal reference) for the symbol.

Example

Display the euro sign, €, with an entity name, a decimal, and a hexadecimal value:

<p>I will display &euro;</p>
<p>I will display &#8364;</p>
<p>I will display &#x20AC;</p>

Will display as:

I will display €
I will display €
I will display €

Some Mathematical Symbols Supported by HTML

Char Number Entity Description
Α &#913; &Alpha; GREEK CAPITAL LETTER ALPHA
Β &#914; &Beta; GREEK CAPITAL LETTER BETA
Γ &#915; &Gamma; GREEK CAPITAL LETTER GAMMA
Δ &#916; &Delta; GREEK CAPITAL LETTER DELTA
Ε &#917; &Epsilon; GREEK CAPITAL LETTER EPSILON
Ζ &#918; &Zeta; GREEK CAPITAL LETTER ZETA

 


Some Other Entities Supported by HTML

Char Number Entity Description
© &#169; &copy; COPYRIGHT SIGN
® &#174; &reg; REGISTERED SIGN
&#8364; &euro; EURO SIGN
&#8482; &trade; TRADEMARK
&#8592; &larr; LEFTWARDS ARROW
&#8593; &uarr; UPWARDS ARROW
&#8594; &rarr; RIGHTWARDS ARROW
&#8595; &darr; DOWNWARDS ARROW
&#9824; &spades; BLACK SPADE SUIT
&#9827; &clubs; BLACK CLUB SUIT
&#9829; &hearts; BLACK HEART SUIT
&#9830; &diams; BLACK DIAMOND SUIT


Using Emojis in HTML (#40)

Emojis are characters from the UTF-8 character set: ? ? ?


What are Emojis?

Emojis look like images, or icons, but they are not.

They are letters (characters) from the UTF-8 (Unicode) character set.

UTF-8 covers almost all of the characters and symbols in the world.


The HTML charset Attribute

To display an HTML page correctly, a web browser must know the character set used in the page.

This is specified in the <meta> tag:

<meta charset=”UTF-8″>

If not specified, UTF-8 is the default character set in HTML.


UTF-8 Characters

Many UTF-8 characters cannot be typed on a keyboard, but they can always be displayed using numbers (called entity numbers):

  • A is 65
  • B is 66
  • C is 67

Example

<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
</head>
<body>

<p>I will display A B C</p>
<p>I will display &#65; &#66; &#67;</p>

</body>
</html>

Example Explained

The <meta charset="UTF-8"> element defines the character set.

The characters A, B, and C, are displayed by the numbers 65, 66, and 67.

To let the browser understand that you are displaying a character, you must start the entity number with &# and end it with ; (semicolon).


Emoji Characters

Emojis are also characters from the UTF-8 alphabet:

  • ? is 128516
  • ? is 128525
  • ? is 128151

Example

<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
</head>
<body>

<h1>My First Emoji</h1>

<p>&#128512;</p>

</body>
</html>

Since Emojis are characters, they can be copied, displayed, and sized just like any other character in HTML.

Example

<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
</head>
<body>

<h1>Sized Emojis</h1>

<p style="font-size:48px">
&#128512; &#128516; &#128525; &#128151;
</p>

</body>
</html>



HTML Forms (#41)

An HTML form is used to collect user input. The user input is most often sent to a server for processing.


Example





The <form> Element

The HTML <form> element is used to create an HTML form for user input:

<form>
.
form elements
.
</form>

The <form> element is a container for different types of input elements, such as: text fields, checkboxes, radio buttons, submit buttons, etc.


The <input> Element

The HTML <input> element is the most used form element.

An <input> element can be displayed in many ways, depending on the type attribute.

Here are some examples:

Type Description
<input type=”text”> Displays a single-line text input field
<input type=”radio”> Displays a radio button (for selecting one of many choices)
<input type=”checkbox”> Displays a checkbox (for selecting zero or more of many choices)
<input type=”submit”> Displays a submit button (for submitting the form)
<input type=”button”> Displays a clickable button

Text Fields

The <input type="text"> defines a single-line input field for text input.

Example

A form with input fields for text:

<form>
  <label for="fname">First name:</label><br>
  <input type="text" id="fname" name="fname"><br>
  <label for="lname">Last name:</label><br>
  <input type="text" id="lname" name="lname">
</form>

This is how the HTML code above will be displayed in a browser:

First name:

Last name:

Note: The form itself is not visible. Also note that the default width of an input field is 20 characters.


The <label> Element

Notice the use of the <label> element in the example above.

The <label> tag defines a label for many form elements.

The <label> element is useful for screen-reader users, because the screen-reader will read out loud the label when the user focus on the input element.

The <label> element also help users who have difficulty clicking on very small regions (such as radio buttons or checkboxes) – because when the user clicks the text within the <label> element, it toggles the radio button/checkbox.

The for attribute of the <label> tag should be equal to the id attribute of the <input> element to bind them together.


Radio Buttons

The <input type="radio"> defines a radio button.

Radio buttons let a user select ONE of a limited number of choices.

Example

A form with radio buttons:

<p>Choose your favorite Web language:</p>

<form>
  <input type="radio" id="html" name="fav_language" value="HTML">
  <label for="html">HTML</label><br>
  <input type="radio" id="css" name="fav_language" value="CSS">
  <label for="css">CSS</label><br>
  <input type="radio" id="javascript" name="fav_language" value="JavaScript">
  <label for="javascript">JavaScript</label>
</form>

This is how the HTML code above will be displayed in a browser:

Choose your favorite Web language:

 
 
 


Checkboxes

The <input type="checkbox"> defines a checkbox.

Checkboxes let a user select ZERO or MORE options of a limited number of choices.

Example

A form with checkboxes:

<form>
<input type=”checkbox” id=”vehicle1″ name=”vehicle1″ value=”Bike”>
<label for=”vehicle1″> I have a bike</label><br>
<input type=”checkbox” id=”vehicle2″ name=”vehicle2″ value=”Car”>
<label for=”vehicle2″> I have a car</label><br>
<input type=”checkbox” id=”vehicle3″ name=”vehicle3″ value=”Boat”>
<label for=”vehicle3″> I have a boat</label>
</form>

This is how the HTML code above will be displayed in a browser:

 
 
 


The Submit Button

The <input type="submit"> defines a button for submitting the form data to a form-handler.

The form-handler is typically a file on the server with a script for processing input data.

The form-handler is specified in the form’s action attribute.

Example

A form with a submit button:

<form action="/action_page.php">
  <label for="fname">First name:</label><br>
  <input type="text" id="fname" name="fname" value="John"><br>
  <label for="lname">Last name:</label><br>
  <input type="text" id="lname" name="lname" value="Doe"><br><br>
  <input type="submit" value="Submit">
</form>

This is how the HTML code above will be displayed in a browser:

First name:

Last name:


The Name Attribute for <input>

Notice that each input field must have a name attribute to be submitted.

If the name attribute is omitted, the value of the input field will not be sent at all.

Example

This example will not submit the value of the “First name” input field:

<form action="/action_page.php">
  <label for="fname">First name:</label><br>
  <input type="text" id="fname" value="John"><br><br>
  <input type="submit" value="Submit">
</form>


HTML Canvas Graphics (#42)

The HTML <canvas> element is used to draw graphics on a web page.

The graphic to the left is created with <canvas>. It shows four elements: a red rectangle, a gradient rectangle, a multicolor rectangle, and a multicolor text.


What is HTML Canvas?

The HTML <canvas> element is used to draw graphics, on the fly, via JavaScript.

The <canvas> element is only a container for graphics. You must use JavaScript to actually draw the graphics.

Canvas has several methods for drawing paths, boxes, circles, text, and adding images.


Browser Support

The numbers in the table specify the first browser version that fully supports the <canvas> element.

Element Chrome FireFox EDGE Safari Opera
<canvas> 4.0 9.0 2.0 3.1 9.0

 


Canvas Examples

A canvas is a rectangular area on an HTML page. By default, a canvas has no border and no content.

The markup looks like this:

<canvas id="myCanvas" width="200" height="100"></canvas>

Note: Always specify an id attribute (to be referred to in a script), and a width and height attribute to define the size of the canvas. To add a border, use the style attribute.

Example

<canvas id="myCanvas" width="200" height="100" style="border:1px solid #000000;">
</canvas>

Add a JavaScript

After creating the rectangular canvas area, you must add a JavaScript to do the drawing.


Draw a Circle

Example

<script>
var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
ctx.moveTo(00);
ctx.lineTo(200100);
ctx.stroke();
</script>

Draw a Text

Example

<script>
var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
ctx.beginPath();
ctx.arc(95504002 * Math.PI);
ctx.stroke();
</script>

Stroke Text

Example

<script>
var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
ctx.font = "30px Arial";
ctx.fillText("Hello World"1050);
</script>

Draw Linear Gradient

Example

<script>
var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");

// Create gradient
var grd = ctx.createLinearGradient(002000);
grd.addColorStop(0"red");
grd.addColorStop(1"white");

// Fill with gradient
ctx.fillStyle = grd;
ctx.fillRect(101015080);
</script>

Draw Circular Gradient

Example

<script>
var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");

// Create gradient
var grd = ctx.createRadialGradient(755059060100);
grd.addColorStop(0"red");
grd.addColorStop(1"white");

// Fill with gradient
ctx.fillStyle = grd;
ctx.fillRect(101015080);
</script>

Draw Image

<script>
var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
var img = document.getElementById("scream");
ctx.drawImage(img, 1010);
</script>


HTML Video (#43)

The HTML <video> element is used to show a video on a web page.

The HTML <video> Element

To show a video in HTML, use the <video> element:

Example

<video width="320" height="240" controls>
  <source src="movie.mp4" type="video/mp4">
  <source src="movie.ogg" type="video/ogg">
Your browser does not support the video tag.
</video>

How it Works

The controls attribute adds video controls, like play, pause, and volume.

It is a good idea to always include width and height attributes. If height and width are not set, the page might flicker while the video loads.

The <source> element allows you to specify alternative video files which the browser may choose from. The browser will use the first recognized format.

The text between the <video> and </video> tags will only be displayed in browsers that do not support the <video> element.


HTML <video> Autoplay

To start a video automatically, use the autoplay attribute:

Example

<video width="320" height="240" autoplay>
  <source src="movie.mp4" type="video/mp4">
  <source src="movie.ogg" type="video/ogg">
Your browser does not support the video tag.
</video>

Note: Chromium browsers do not allow autoplay in most cases. However, muted autoplay is always allowed.

Add muted after autoplay to let your video start playing automatically (but muted):

Example

<video width="320" height="240" autoplay muted>
  <source src="movie.mp4" type="video/mp4">
  <source src="movie.ogg" type="video/ogg">
Your browser does not support the video tag.
</video>

HTML Video Formats

There are three supported video formats: MP4, WebM, and Ogg. The browser support for the different formats is:

Browser MP4 WebM Ogg
Edge YES YES YES
Chrome YES YES YES
Firefox YES YES YES
Safari YES YES NO
Opera YES YES YES

HTML Video – Media Types

File Format Media Type
MP4 video/mp4
WebM video/webm
Ogg video/ogg

HTML Video – Methods, Properties, and Events

The HTML DOM defines methods, properties, and events for the <video> element.

This allows you to load, play, and pause videos, as well as setting duration and volume.

There are also DOM events that can notify you when a video begins to play, is paused, etc.



HTML Audio (#44)

The HTML <audio> element is used to play an audio file on a web page.


The HTML <audio> Element

To play an audio file in HTML, use the <audio> element:

Example

<audio controls>
  <source src="horse.ogg" type="audio/ogg">
  <source src="horse.mp3" type="audio/mpeg">
Your browser does not support the audio element.
</audio>

HTML Audio – How It Works

The controls attribute adds audio controls, like play, pause, and volume.

The <source> element allows you to specify alternative audio files which the browser may choose from. The browser will use the first recognized format.

The text between the <audio> and </audio> tags will only be displayed in browsers that do not support the <audio> element.


HTML <audio> Autoplay

To start an audio file automatically, use the autoplay attribute:

Example

<audio controls autoplay>
  <source src="horse.ogg" type="audio/ogg">
  <source src="horse.mp3" type="audio/mpeg">
Your browser does not support the audio element.
</audio>

Note: Chromium browsers do not allow autoplay in most cases. However, muted autoplay is always allowed.

Add muted after autoplay to let your audio file start playing automatically (but muted):

Example

<audio controls autoplay muted>
  <source src="horse.ogg" type="audio/ogg">
  <source src="horse.mp3" type="audio/mpeg">
Your browser does not support the audio element.
</audio>

HTML Audio Formats

There are three supported audio formats: MP3, WAV, and OGG. The browser support for the different formats is:

Browser MP3 WAV OGG
Edge/IE YES YES* YES*
Chrome YES YES YES
Firefox YES YES YES
Safari YES YES NO
Opera YES YES YES

 


HTML Audio – Media Types

File Format Media Type
MP3 audio/mpeg
OGG audio/ogg
WAV audio/wav

HTML Audio – Methods, Properties, and Events

The HTML DOM defines methods, properties, and events for the <audio> element.

This allows you to load, play, and pause audios, as well as set duration and volume.

There are also DOM events that can notify you when an audio begins to play, is paused, etc.



HTML Plug-ins (#45)

Plug-ins are computer programs that extend the standard functionality of the browser.


Plug-ins

Plug-ins were designed to be used for many different purposes:

  • To run Java applets
  • To run Microsoft ActiveX controls
  • To display Flash movies
  • To display maps
  • To scan for viruses
  • To verify a bank id

Warning !

Most browsers no longer support Java Applets and Plug-ins.

ActiveX controls are no longer supported in any browsers.

The support for Shockwave Flash has also been turned off in modern browsers.


The <object> Element

The <object> element is supported by all browsers.

The <object> element defines an embedded object within an HTML document.

It was designed to embed plug-ins (like Java applets, PDF readers, and Flash Players) in web pages, but can also be used to include HTML in HTML:

Example

<object width="100%" height="500px" data="snippet.html"></object>

Or images if you like:

Example

<object data="audi.jpeg"></object>

The <embed> Element

The <embed> element is supported in all major browsers.

The <embed> element also defines an embedded object within an HTML document.

Web browsers have supported the <embed> element for a long time. However, it has not been a part of the HTML specification before HTML5.

Example

<embed src="audi.jpeg">

Note that the <embed> element does not have a closing tag. It can not contain alternative text.

The <embed> element can also be used to include HTML in HTML:

Example

<embed width="100%" height="500px" src="snippet.html">


HTML Uniform Resource Locators (#46)

A URL is another word for a web address.

A URL can be composed of words (e.g. w3schools.com), or an Internet Protocol (IP) address (e.g. 192.68.20.50).

Most people enter the name when surfing, because names are easier to remember than numbers.


URL – Uniform Resource Locator

Web browsers request pages from web servers by using a URL.

A Uniform Resource Locator (URL) is used to address a document (or other data) on the web.

A web address like https://apostube.com/ follows these syntax rules:

scheme://prefix.domain:port/path/filename

Explanation:

  • scheme – defines the type of Internet service (most common is http or https)
  • prefix – defines a domain prefix (default for http is www)
  • domain – defines the Internet domain name (like w3schools.com)
  • port – defines the port number at the host (default for http is 80)
  • path – defines a path at the server (If omitted: the root directory of the site)
  • filename – defines the name of a document or resource

Common URL Schemes

The table below lists some common schemes:

Scheme Short for Used for
http HyperText Transfer Protocol Common web pages. Not encrypted
https Secure HyperText Transfer Protocol Secure web pages. Encrypted
ftp File Transfer Protocol Downloading or uploading files
file A file on your computer


URL Encoding

URLs can only be sent over the Internet using the ASCII character-set. If a URL contains characters outside the ASCII set, the URL has to be converted.

URL encoding converts non-ASCII characters into a format that can be transmitted over the Internet.

URL encoding replaces non-ASCII characters with a “%” followed by hexadecimal digits.

URLs cannot contain spaces. URL encoding normally replaces a space with a plus (+) sign, or %20.


Try It Yourself

 

If you click “Submit”, the browser will URL encode the input before it is sent to the server.

A page at the server will display the received input.

Try some other input and click Submit again.


ASCII Encoding Examples

Your browser will encode input, according to the character-set used in your page.

The default character-set in HTML5 is UTF-8.

Character From Windows-1252 From UTF-8
%80 %E2%82%AC
£ %A3 %C2%A3
© %A9 %C2%A9
® %AE %C2%AE
À %C0 %C3%80
Á %C1 %C3%81
 %C2 %C3%82
à %C3 %C3%83
Ä %C4 %C3%84
Å %C5 %C3%85