Dolby Digital (DD for short) is a sound compression system which is used by media formats like DVD and Bluray. Developed by Dolby Laboratories, Dolby Digital made it's debut in UK cinema's in 1992. The first movie to use the Dolby sound compression was Batman Returns; directed by Tim Burton and starring Danny Devito as the Penguin.

The most common domestic version of Dolby Digital (2011) is 5.1; which uses five speakers and a subwoofer. But, there are many versions currently available, such as 2.1 and 7.1. The current DD format list at the end of 2008 is as follows,

- Digital Digital - Is the standard 5.1 channels of data. Used by standard DVD's and DVD players.

- Digital Digital Ex - Is the same system as 5.1, but adding one or two extra channels, for 6.1 and 7.1

- Digital Digital Surround Ex - Developed in conjunction with THX, it provides extra compatibility for the above two DD formats.

- Digital Digital Live - Created for computer games to support DD 5.1, and is compatible with sound manufacturers like Creative.

- Digital Digital Plus - A juiced up version of DD, it can support numerous extraneous channels, up to thirteen.

- Digital Digital TrueHD - Developed for the new media formats like Bluray and DVD HD.

Dolby Digital is changing with the times, is always improving and finding new applications. Dolby were involved in the creation of the audio coding for MPEG - which is a guild of motion picture editors, who aim to create standards for both audio and video encoding.

Dolby has been an integral part of DVD and DVD HD development, and has become a mandatory audio codec for both of these formats. Because Bluray was the brain child of Sony, DD is only an optional codec for this format - this may effect the future exposure of DD. Sony appear to have won the format war between Bluray and DVD HD, with Hollywood studios beginning to release their movies only on Bluray. The widespread adoption of Bluray may signal the death of the HD DVD format.