World of Warcraft, or WoW, is a large multiplayer online role-playing game by Blizzard Entertainment. It is the fourth episode in the fantasy Warcraft world since 1994. World of Warcraft takes place within the Warcraft world of Azeroth, approximately four years after the events at the conclusion of Blizzard's previous Warcraft release, Warcraft III: The Frozen Throne.

The first expansion set of the game, The Burning Crusade, was released in January, 2007. The second expansion set, Wrath of the Lich King, was released in November, 2008. The third expansion set, Cataclysm, was announced at BlizzCon 2009, and entered into closed beta testing in late June 2010.

With more than 12 million monthly subscriptions, World of Warcraft is one of the world's most-subscribed multiplayer online role-playing games. It also holds the Guinness World Record for the most popular multiplayer online role-playing game by subscribers.