A massively multiplayer online game (also called MMO and MMOG) is a multiplayer video game which is capable of supporting hundreds or thousands of players simultaneously. By necessity, they are played on the Internet, and usually feature at least one persistent world.

A massively multiplayer online game (also called MMO and MMOG) is a multiplayer video game which is capable of supporting hundreds or thousands of players simultaneously. By necessity, they are played on the Internet, and usually feature at least one persistent world.