MPQ (short for "MoPaQ", supposedly derived from Mike O'Brien Pack) is the name of a file extension and type of proprietary data file used by World of Warcraft through the Mists of Pandaria expansion; although it is used in various other games by Blizzard Entertainment. With the Warlords of Draenor expansion, Blizzard has transitioned to a new proprietary format called CASC (Content Addressable Storage Container).