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. Many games have at least one persistent world, however others just have large numbers of players competing at once in one form or another without any lasting effect to the world at all. These games can be played on any platform it, be it the personal computer, a game console such as the internet capable PlayStation Portable|PSP, PlayStation 3, Xbox 360, Nintendo DS, PS Vita or Wii, or mobile devices and smartphones based on such operating systems as Android (operating system)|Android, iOS (Apple)|iOS and Windows Phone.
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.