GlossaryCaptioning types
Closed captions
Also known as: CC
Captions that the viewer can toggle on or off — typically rendered as overlay text on video, controlled by the playback environment.
Closed captions are 'closed' in the sense that they're not burned into the video; they exist as a separate track that the viewer can enable or disable. The CC button in video players controls this.
Closed captions are the dominant form on the web because they preserve viewer choice, support multiple languages on the same recording, and are more accessible to assistive technology than burned-in captions.
WCAG 2.2 success criterion 1.2.4 (Captions, Live) and 1.2.2 (Captions, Prerecorded) both apply to captions regardless of open or closed delivery; what matters is whether captions are present and synchronized.