Massive multiplayer online role-playing game MMORPG is a genre of online role-playing video games RPGs in which a large number of players interact with one another in a virtual world.

As in all RPGs, players assume the role of a fictional character most commonly in a fantasy setting and take control over many of that character's actions. MMORPGs are distinguished from single-player or small multi-player RPGs 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, with combined global memberships in subscription and non-subscription games exceeding 15 million as of 2006. Worldwide revenues for MMORPGs exceeded half a billion dollars in 2005,and Western revenues exceeded one billion USD in 2006.