The Advanced Access Content System (AACS) is a standard for content distribution and digital rights management, intended to restrict access to and copying of the post-DVD generation of optical discs. The specification was publicly released in April 2005 and the standard has been adopted as the access restriction scheme for HD DVD and Blu-ray Disc (BD). It is developed by AACS Licensing Administrator, LLC (AACS LA), a consortium that includes Disney, Intel, Microsoft, Panasonic, Warner Bros., IBM, Toshiba and Sony. AACS has been operating under an "interim agreement" since the final specification (including provisions for Managed Copy) has not yet been finalized.

Since appearing in devices in 2006, several AACS decryption keys have been extracted from software players and published on the Internet, allowing decryption by unlicensed software.