World of Warcraft is a 2004 massively multiplayer online role-playing game (MMORPG) developed by Blizzard Entertainment for the PC and Mac. The game is estimated to have approximately 10 million subscribers, and is widely considered to be the most successful and popular MMORPG to date.

World of Warcraft takes place in the world of Azeroth, the fantasy setting of Blizzard's other six Warcraft real-time strategy games, including 2002's Reign of Chaos. The inhabitants of WoW are divided into two warring factions, the Alliance and The Horde. The Alliance consists of Humans, Night Elves, Dwarfs, Gnomes and Draenei, while The Horde consists of Orcs, Tauren, Undead, Trolls and Blood Elves. The two factions are constantly warring with each other throughout Azeroth, fighting over land and resources. WoW begins four years after the events in The Frozen Throne.

At the beginning of the game you will be able to create your own character, choosing a number of different customizations: faction, race, class, sex, name, appearance and others. The nine different classes you can choose in the game are as follows: Druid, Hunter, Mage, Paladin, Priest, Rogue, Shaman, Warlock and Warrior. Upon entering the World of Warcraft, you begin to accept quests from NPCs (non-playable characters) in towns, converse and play with other online players, buy items and equipment, and in general adventure thorughout Azeroth. As you play the game, completing quests and defeating foes, you will level up and gain new abilities. The specific ability “tree” you follow is up to you, and is part of the customizable aspect of your character. In addition to normal playable quests, there are also certain highly rewarded “instance” dungeons, where players can join together to form a large party, plunder a dungeon and acquire valuable loot.

In March 2009, Worlds.com CEO Thom Kidrin claimed that the company planned to sue both Second Life and World of Warcraft's developer Blizzard. Kidrin says that a scalable virtual world with thousands of users is his company's patented intellectual property. He says that any company which does not enter into licensing negotiations with Worlds.com should expect a lawsuit. NCSoft, developer of City of Heroes and Guild Wars, has already been sued by Worlds for intellectual property violations.Silicon alley Insider: Worlds.com CEO: We're 'Absolutely' Going To Sue Second Life