World of Warcraft (commonly known as WoW) is a massively multiplayer online role-playing game (MMORPG). It is Blizzard Entertainment's fourth game set in the fantasy Warcraft universe, which was 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. It is currently the world's largest MMORPG in terms of monthly subscribers. World of Warcraft currently holds 62% of the MMOG market at 10 million subscribers. The current subscriber base for all MMOGs is 16 million.

The first official expansion pack of the game, The Burning Crusade, was released on January 16, 2007. During the 2007 BlizzCon event, Blizzard announced a second expansion pack called Wrath of the Lich King on August 3, 2007.

Unlike previous games in the Warcraft series, World of Warcraft is a MMORPG, not a real-time strategy game. As with other MMORPGs, people control a character avatar within a persistent game world, exploring the landscape, fighting monsters, performing quests, building skills, and interacting with NPCs, as well as other players. The game rewards success with in-game money, items, experience and reputation, all of which in turn allow players to improve their skill and power. Players can level up their characters from level one to level 60, level 70 if they have The Burning Crusade expansion. Upon release of the Wrath of the Lich King expansion, players will be able to attain level 80 after purchasing the expansion. In addition, players may opt to take part in battles against other players of an enemy faction, in PvP battlegrounds or in normal world zones subject to the rules in place on the particular server. Duels can also be fought between members of the same or opposing factions, although these do not provide tangible rewards. Many players also choose to join guilds. Short-term parties and raid groups can be formed to conduct raids against enemy territories and instances.