Void Elements

Introduction#

Not all HTML tags are of the same structure. While most elements require an opening tag, a closing tag, and contents, some elements - known as void elements - only require an opening tag as they themselves do not contain any elements. This topic explains and demonstrates the proper usage of void elements in HTML

Remarks#

A void element cannot have any content but may have attributes. Void elements are self-closing, so they must not have a closing tag.

In HTML5, the following elements are void:

area
base
br
col
embed
hr
img
input
keygen
link
meta
param
source
track
wbr

Void elements

HTML 4.01/XHTML 1.0 Strict includes the following void elements:

area - clickable, defined area in an image
base - specifies a base URL from which all links base
br - line break
col - column in a table [deprecated]
hr - horizontal rule (line)
img - image
input - field where users enter data
link - links an external resource to the document
meta - provides information about the document
param - defines parameters for plugins

HTML 5 standards include all non-deprecated tags from the previous list and

command - represents a command users can invoke [obsolete]
keygen - facilitates public key generation for web certificates [deprecated]
source - specifies media sources for picture, audio, and video elements

The example below does not include void elements:

<div>
    <a href="https://stackoverflow.com/">
        <h3>Click here to visit <i>Stack Overflow!</i></h3>
    </a>
    <button onclick="alert('Hello!');">Say Hello!</button>
    <p>My favorite language is <b>HTML</b>. Here are my others:</p>
    <ol>
        <li>CSS</li>
        <li>JavaScript</li>
        <li>PHP</li>
    </ol>
</div>

Notice how every element has an opening tag, a closing tag, and text or other elements inside the opening and closing tags. Void tags however, are shown in the example below:

<img src="https://cdn.sstatic.net/Sites/stackoverflow/company/img/logos/so/so-icon.png" />
<br>
<hr>
<input type="number" placeholder="Enter your favorite number">

With the exception of the img tag, all of these void elements have only an opening tag. The img tag, unlike any other tag, has a self closing / before the greater than sign of the opening tag. It is best practice to have a space before the slash.