Compact disc

The compact disc (CD) is a digital optical disc data storage format that was co-developed by Philips and Sony to store and play digital audio recordings. The first compact disc was manufactured in August 1982, and was first released in Japan in October 1982 as ''Compact Disc Digital Audio''. The CD was more compact than the LaserDisc (LD) developed in the 1970s. The CD gained rapid popularity in the 1990s. It quickly outsold all other audio formats in the United States by 1991, ending the market dominance of the phonograph record and the cassette tape. By 2000, the CD accounted for 92.3% of the entire market share in regard to music sales. The CD is considered the last dominant audio format of the album era, as the rise of MP3, iTunes, cellular ringtones, and other downloadable music formats in the mid-2000s ended the decade-long dominance of the CD.

The ''Digital Audio'' format was later adapted (as CD-ROM) for general-purpose data storage. Several other formats were further derived, including write-once audio and data storage (CD-R), rewritable media (CD-RW), Video CD (VCD), Super Video CD (SVCD), Photo CD, Picture CD, Compact Disc-Interactive (CD-i), Enhanced Music CD, and Super Audio CD (SACD) which may have a CD-DA layer.

Standard CDs have a diameter of and are designed to hold up to 74 minutes of uncompressed stereo digital audio or about of data. Capacity is routinely extended to 80 minutes and by arranging data more closely on the same-sized disc. The Mini CD has various diameters ranging from ; they are sometimes used for CD singles, storing up to 24 minutes of audio, or delivering device drivers.

At the time of the technology's introduction in 1982, a CD could store much more data than a personal computer hard disk drive, which would typically hold 10 MiB. By 2010, hard drives commonly offered as much storage space as a thousand CDs, while their prices had plummeted to commodity levels. In 2004, worldwide sales of audio CDs, CD-ROMs, and CD-Rs reached about 30 billion discs. By 2007, 200 billion CDs had been sold worldwide. Provided by Wikipedia