Multimedia content on the Web, by its definition - including or involving the use of several media - would seem to be inherently accessible or easily made accessible.

However, if the information is audio, such as a RealAudio feed from a news conference or the proceedings in a courtroom, a person who is deaf or hard of hearing cannot access that content unless provision is made for a visual presentation of audio content. Similarly, if the content is pure video, a blind person or a person with severe vision loss will miss the message without the important information in the video being described.

A transcript of audio content is a word-for-word textual representation of the audio, including descriptions of non-text sounds like "laughter" or "thunder." Transcripts of audio content are valuable not only for persons with disabilities but in addition, they permit searching and indexing of that content which is not possible with just the audio.

When a transcript of the audio part of an audio-visual (multimedia) presentation is displayed synchronously with the audio-visual presentation, it is called captioning . When speaking of TV captioning, open captions are those in which the text is always present on the screen and closed captions are those viewers can choose to display or not.

Descriptive video or described video intersperses explanations of important video with the normal audio of a multimedia presentation. These descriptions are also called audio descriptions .