HTML <source> Tag

The HTML <source> tag is used to specify multiple media resources on media elements (such as the <audio> and <video> elements).

The <source> tag allows you to specify alternative video and audio files which the browser may choose from based on its media type or codec support.


The <source> tag is written as <source src="" type=""> (no end tag) with the URL of the media listed between the double quotes of the src attribute. The type attribute can be used to specify the type of the media resource. This helps the browser determine whether or not it can play the media resource before downloading it.

Like this:


Basic tag usage

The codecs Parameter

You might also need to provide the codecs parameter to specify exactly how the resource has been encoded.

Like this:

For examples of values that can be used with the codecs parameter, see the official specifications (listed below).


Attributes can be added to an HTML element to provide more information about how the element should appear or behave.

There are 3 kinds of attributes that you can add to your HTML tags: Element-specific, global, and event handler content attributes.

The <source> element accepts the following attributes.

Element-Specific Attributes

This table shows the attributes that are specific to the <source> tag/element.

srcSpecifies the location of the audio/video file. Its value must be the URL of an audio/video file.
typeSpecifies the type of the embedded content. If specified, the value must be a MIME type.

mediaSpecifies the type of media resource, so the browser can determine whether it can play it or not. If not, it can choose not to download it. If specified, the value must be a valid media query.

Global Attributes

The following attributes are standard across all HTML5 elements. Therefore, you can use these attributes with the <source> tag , as well as with all other HTML tags.

For a full explanation of these attributes, see HTML 5 global attributes.

Event Handler Content Attributes

Event handler content attributes enable you to invoke a script from within your HTML. The script is invoked when a certain "event" occurs. Each event handler content attribute deals with a different event.

Below are the standard HTML5 event handler content attributes.

Again, you can use any of these with the <source> element, as well as any other HTML5 element.

For a full explanation of these attributes, see HTML 5 event handler content attributes.

Differences Between HTML 4 & HTML 5

The <source> element is new in HTML5.

For more information on this element, see HTML5 <source> Tag. Also check out the links to the official specifications below.


Here's a template for the <source> tag with all available attributes for the tag (based on HTML5). These are grouped into attribute types, each type separated by a space. In many cases, you will probably only need one or two (if any) attributes. Simply remove the attributes you don't need.

For more information on attributes for this tag, see HTML5 <source> Tag.

Tag Details

For more details about the <source> tag, see HTML5 <source> Tag.


Here are the official specifications for the <source> element.

What's the Difference?

W3C creates "snapshot" specifications that don't change once defined. So the HTML5 specification won't change once it becomes an official recommendation. WHATWG on the other hand, develops a "living standard" that is updated on a regular basis. In general, you will probably find that the HTML living standard will be more closely aligned to the current W3C draft than to the HTML5 specification.