Closed captions (Abbreviated as CC) are a text version of the spoken part of a movie, computer presentation or television program. Sometimes, they include descriptions of non-speech elements (For example, “machinery starting up”). It can be stored separately or embedded within the video. The common formats are WebVTT, SRT, DFXP and TTML. The viewer has the power to deactivate the closed captioning in a video.

Closed captioning was developed for hearing impaired people. However, it can be useful in situations where audio cannot be heard due to noisy environment (Airports, Railway Stations) or where one need to mute the sound of a video (Hospitals). Also, it is beneficial for foreigners to watch a movie or television program.