Optical disc

Optical disc, thin, flat, circular plastic plate covered with a reflective substance that receives coded information from a laser beam to record sound, data, or pictures. The beam marks the disc, which can be stored or decoded by a weaker laser upon playback. Some optical discs have only prerecorded material, which cannot be erased. Optical discs have a greater storage capacity and wear longer than magnetic discs.

See also: Videodisc; Compact disc (CD).