World of Warcraft (WoW) is a 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. The Warcraft universe is a fictional universe in an ethereal plane called The Twisting Nether. Known worlds include Azeroth, Draenor, Argus, K'aresh, and Xoroth. The majority of media in the Warcraft universe takes place upon a planet called Azeroth. This planet has three continents, named the Eastern Kingdoms, Kalimdor, and Northrend, all of which are separated by a giant ocean called the Great Sea. Time is entirely independent of the Christian calender with the year 0 marking the events taking place in the first releaser of the game Warcraft: Orcs & Humans.