Massively multiplayer online role-playing game (MMORPG) is a genre of computer role-playing games (CRPGs) in which a large number of players interact with one another in a virtual world. The term MMORPG was coined by Richard Garriott, the creator of Ultima Online, the game credited with popularizing the genre in 1997.

As in all RPGs, players assume the role of a fictional character (most commonly in a fantasy world), and take control over many of that character's actions. MMORPGs are distinguished from single-player or small multi-player CRPGs by the number of players, and by the game's persistent world, usually hosted by the game's publisher, which continues to exist and evolve while the player is away from the game.

MMORPGs are very popular throughout the world. Worldwide revenues for MMORPGs exceeded half a billion dollars in 2005, and Western revenues exceeded one billion USD in 2006