A massively multiplayer online game (also called MMO) 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 feature at least one persistent world. They are, however, not necessarily games played on personal computers.
Most of the newer game consoles, including the PSP, PlayStation 3, Xbox 360, Nintendo DSi and Wii can access the Internet and may therefore run MMO games. Additionally, mobile devices and smartphones based on such operating systems as Windows Mobile and Google's Android, as well as the Apple iPhone are seeing an increase in the amount of MMO games available.
MMOGs can enable players to cooperate and compete with each other on a large scale, and sometimes to interact meaningfully with people around the world. They include a variety of gameplay types, representing many video game genres.