Search engines work exclusively through words. By adding transcripts and captions to audio and video files, organizations can ensure that their content can be indexed and searchable while increasing rankings.
Subtitles are designed for hearing users, as they only cover spoken text and do not include sound effects or other audio elements. SDH, on the other hand, are designed for those who are deaf or hard of hearing, by including additional information, such as speaker tags, sound effects and other elements outside of speech. Closed captions are required by law on all public broadcasts, as per FCC regulations and are typically formatted as white text on a black background that can be positioned anywhere on the screen.