World of Warcraft is a MMORPG created by Blizzard Entertainment . World of Warcraft , often referred to as WoW , is a massively multiplayer online role-playing game ( MMORPG ) by Blizzard Entertainment , a subsidiary of Activision Blizzard . It is the fourth released game set in the fantasy Warcraft universe , which was first introduced by Warcraft : Orcs & Humans in 1994 .