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.

According to wikipedia, MMORPGs are very popular throughout the world, with combined global memberships in subscription and non-subscription games exceeding 15 million as of 2006.