What is "mpq"

MPQ (Mo'PaQ, short for Mike O'Brien Pack, named after its creator), is an archiving file format used in several of Blizzard Entertainment's games.

MPQs used in Blizzard's games generally contain a game's data files, including graphics, sounds, and level data. The format's capabilities include compression, encryption, file segmentation, extensible file metadata, cryptographic signature and the ability to store multiple versions of the same file for internationalization and platform-specific differences. MPQ archives can use a variety of compression algorithms which may also be combined.