World of Warcraft (commonly known as WoW) is a pay-to-play massively multiplayer online role-playing game. It is Blizzard Entertainment's fourth game set in the fantasy Warcraft universe, first introduced by Warcraft: Orcs & Humans in 1994. World of Warcraft takes place within the world of Azeroth, four years after the events at the conclusion of Blizzard's previous release, Warcraft III: The Frozen Throne. Blizzard Entertainment announced World of Warcraft on September 2, 2001. The game was released on November 23, 2004, celebrating the 10th anniversary of the Warcraft franchise.

Although its initial release was hampered by overpopulated servers, the game became a financial success and the world's largest MMORPG in terms of monthly subscribers. On July 24, 2007, Blizzard announced that the user base for World of Warcraft had reached a new milestone, with 9 million players worldwide. There are more than 2 million players in North America, 1.5 million players in Europe, and 3.5 million players in China as of January, 2007. The game has won numerous awards and recognitions, including GameSpot's Game of the Year Award for 2004.

The first official expansion pack of the game, The Burning Crusade, was released on January 16, 2007. Blizzard announced a second expansion pack called Wrath of the Lich King on August 3, 2007. The release date of Wrath of the Lich King has not yet been announced.