Optical disc

The bottom surface of a 12 cm compact disc (CD-R), showing characteristic iridescence.
The optical lens of a compact disc drive.
LaserCard made by Drexler Technology Corporation.

An optical disc is a flat, usually[note 1] disc-shaped object that stores information in the form of physical variations on its surface that can be read with the aid of a beam of light. Optical discs can be reflective, where the light source and detector are on the same side of the disc, or transmissive, where light shines through the disc to be detected on the other side.

Optical discs can store analog information (e.g. Laserdisc), digital information (e.g. DVD), or store both on the same disc (e.g. CD Video).

Their main uses are the distribution of media and data, and long-term archival.
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