Dolby Digital is the name for audio compression technologies developed by Dolby Laboratories. It was originally named Dolby Stereo Digital until 1994. Except for Dolby TrueHD, the audio compression is lossy. The first use of Dolby Digital was to provide digital sound in cinemas from 35mm film prints. It is now also used for other applications such as HDTV broadcast, DVDs, Blu-ray Discs and game consoles.
Read more about Dolby Digital: Dolby Digital in The Cinema, Versions, Channel Configurations, Applications, Dolby Technologies in Packaged Media Formats, Technical Details, Liba52