The goal for closed captioning is to provide an alternate representation (usually text) for all information in a media piece whether it is audio, video or animation.  In addition, closed captioning implies that the captions are synchronized with the audio content. It also includes the description of sounds (e.g., "... the dog barks...") as well as the use of symbols (icons) to represent the type of content (e.g., a musical note could be used for music).

Most users of closed captioning are not deaf. It is used by people who want to learn a second language, people viewing in a noisy environment, students learning to read, and for several other reasons. Furthermore, it is likely that closed captioning will become a mainstream solution as multimedia noise pollution increases in the classroom, library, and workplace.

For more information on captioning standards, including multimedia captioning, check the following sources:

Microsoft Accessibility Web Site

National Captioning Institute (select "What's Captioning?")