13. What are the differences between Closed Captions and subtitles ?
Closed Captions, also known as CC, are a standardized encoding method to incorporate textual information into an NTSC television signal. The European equivalent of Closed Captions is PAL Teletext. The text characters of the captions can be displayed by any regular TV with a built-in decoder or by attaching a separate caption decoder unit.

Most television units larger than 13 inches sold in the US since 1993 have the Closed Caption decoder circuitry built-in. Closed Captions analog signals can be embedded on standard videotape, broadcast TV, cable TV. On DVD, Closed Captions are encoded in a specific data channel of the MPEG-2 video stream and are decoded by the DVD player. Captions are different from subtitles in the sense that captions usually represents the on-screen text specifically designed for hearing impaired viewers, while subtitles are straight translations of the movie dialogue. Subtitles are encoded as subpicture streams and up to 32 different subpictures can be used to represent different language translations.

Captions usually include the descriptions of background sounds and music, such as "bells...", "footsteps...", "shouting in distance...", etc. Closed Captions are usually not visible until the viewer activates them, while Open Captions are always visible.

Most remote controls have the CC button to activate Closed Captions and the Subtitle button to display the subtitle streams.