Closed captioning and subtitling are both processes of displaying text on a television, video screen, or other visual display to provide additional or interpretive information. Wikipedia

A process of displaying text on a visual display, such as a TV screen Wikipedia Disambiguation

Used to provide the text of a show's audio portion to those who may have trouble hearing it Wikidata

The display of text on a television or video screen, usually a transcription of the audio portion of a program as it occurs (either verbatim or in edited form), most frequently used by the deaf and language learners. Closed captions are encoded invisibly, and displayed by a decoder. Wiktionary