Compact disc
Compact disc (CD) is a digital optical disc data storage format that was co-developed by Philips and Sony and released in 1982. The format was originally developed to store and play only sound recordings (CD-DA) 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. The first commercially available audio CD player, the Sony CDP-101, was released October 1982 in Japan.
History of sound recording
Although a number of short-lived "hybrid" studio and consumer technologies appeared in this period (e.g. Digital Audio Tape or DAT, which recorded digital signal samples onto standard magnetic tape), Sony assured the preeminence of its new digital recording system by introducing, together with Philips, the most advanced consumer audio format to date — the digital compact disc (CD). The Compact disc rapidly replaced both the 12" album and the 7" single as the new standard consumer format, and ushered in a new era of high-fidelity consumer audio — CDs were small, portable and durable, and they could reproduce the entire audible sound spectrum, with unrestricted dynamic range, perfect clarity and no distortion. Because CDs were encoded and read optically, using a laser beam, there was no physical contact between the disc and the playback mechanism, so a well-cared-for CD could be played over and over, with absolutely no degradation or loss of fidelity. CDs also represented a considerable advance in both the physical size of the medium, and its storage capacity — LPs could only practically hold about 50 minutes of audio, because they were physically limited by the size of the disc itself and the density of the grooves that could be cut into it — the longer the recording, the closer together the grooves and thus the lower the overall fidelity; CDs, on the other hand they were less than half the overall size of the old 12" LP format, but offered about double the duration of the average LP, with up to 80 minutes of audio.