While subtitles are intended for viewers who don't understand the language being spoken, captions are intended for viewers who can’t hear the audio. Captions include the dialogue as well as any other relevant audio (examples: [laughter], [applause], [ominous music]). Users can usually select captioning by clicking the CC icon.
Closed vs. open captions? Closed captions mean that the captions are on a separate track that can be turned on or off, usually by pressing the “CC” button. Open captions are always showing and can’t be turned on or off.