alternative content

Web content that is used in place of other content that some people are not able to access. Alternative content fulfills essentially the same function or purpose as the original content. WCAG 2.0 recognizes several general types of alternative content:

• text alternatives for text content: Text that is programmatically associated with text content to provide expanded information. For example, an abbreviation (or acronym) may provide an expansion of the shortened word or initialized words (<abbr title="User Agent Accessibility Guidelines">UAAG</abbr>).
• text alternatives for non-text content: Text that is programmatically associated with non-text content or referred to from text that is programmatically associated with non-text content. For example, an image of a chart might have two text alternatives: a description in the paragraph after the chart and a short text alternative for the chart indicating in words that a description follows.
• alternatives for time-based media: Web content that serves the same function or purpose as one or more tracks in a time-based media presentation. This includes: captions, audio descriptions, extended audio descriptions, sign language interpretation as well as correctly sequenced text descriptions of time-based visual and auditory information that also is capable of achieving the outcomes of any interactivity in the time-based presentation.
• media alternative for text: Media that presents no more information than is already presented in text (directly or via text alternatives). A media alternative for text is provided for people who benefit from alternate representations of text. Media alternatives for text may be audio-only, video-only (including sign-language video), or audio-video.