A Compact Disc (CD) is a type of optical disc. It is flat and round, and is used to store digital data. It was first used to store music and other sounds. The sound on a CD is played using a compact disc player. It was developed by Philips and Sony.
The diameter of a normal CD is 120 mm. The middle hole in a CD is about the size of a five cent coin (about 1.5 cm).
Later, Compact Discs were made that could be used to store computer files in the same way as audio compact discs. These are called CD-ROMsThe computer reads the disc using a CD-ROM drive.