::Compact disc


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Compact disc (CD) is a digital optical disc data storage format. The format was originally developed to store and play only sound recordings but was later adapted for storage of data (CD-ROM). Several other formats were further derived from these, including write-once audio and data storage (CD-R), rewritable media (CD-RW), Video Compact Disc (VCD), Super Video Compact Disc (SVCD), Photo CD, PictureCD, CD-i, and Enhanced Music CD. Audio CDs and audio CD players have been commercially available since October 1982.

Standard CDs have a diameter of {{safesubst:#invoke:convert|convert}} and can hold up to about 80 minutes of uncompressed audio or about 700 MiB of data. The Mini CD has various diameters ranging from {{safesubst:#invoke:convert|convert}}; 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 had greater capacity than a personal computer hard drive. By 2010 hard drives commonly had capacities exceeding those of CDs by a factor of several thousand.

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.<ref name="AutoMR-1" /> CDs are increasingly being replaced by other forms of digital storage and distribution, with the result that audio CD sales rates in the U.S. have dropped about 50% from their peak; however, they remain one of the primary distribution methods for the music industry.<ref name="AutoMR-2" />

Compact disc sections
Intro   History    Physical details    Logical formats    Manufacture    Writable compact discs    Copy protection    See also    References    Further reading    External links   

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