Captions exist to make a video’s audio accessible to audiences with hearing needs or who prefer reading along. Captioning provides access to individuals who are deaf or have hearing loss and is often used in places where it is difficult to hear a TV program, such as restaurants and exercise facilities.
They are similar to dialogue-only subtitles, except captions convey not only the content of spoken dialogue, but also equivalents for non-dialogue audio information needed to understand the program content, including sound effects, music, laughter, speaker identification and location. They may be open (permanent) or closed (the viewer may turn them on or off.) Closed captions can be displayed and hidden by the user.