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.
Compulsory dance
The first CDs were developed during the 1930s by teams from Great Britain, who dominated ice dance for most of the early years after the sport was contested at the World Championships in 1952. The CD's prominence in ice dance slowly declined, until it was removed and replaced by the short dance (SD) in 2011, the same year the ISU voted to follow the structure of ice dance competitions by eliminating the CD and original dance (OD) and include the SD and free dance (FD).