Massive Multiplayer Online Games

A Massively Multiplayer Online Game (MMOG or MMO) is a computer game set in a persistent virtual world in which potentially thousands of players may interact together over the Internet. This enables players to interact with and compete against people from around the world. Most of these games are subscription-based, although some recent games (e.g. MapleStory and RuneScape) allow users to play online with no monthly fees.

To support the thousands of players in a MMO game, a number of different servers are often used to divide players into smaller groups. In most cases, the game world is copied onto different servers, called a 'sharded' universe. In some games, a single universe is divided among servers, requiring players to switch servers when they need to access that area of the map.

The most popular type of MMO is the fantasy role playing game (MMORPG), such as World of Warcraft (currently 8 million players), Lineage II (1.3 million players), Final Fantasy XI (500,000 players), EverQuest (200,000 players) and City of Heroes/Villains (130,000 players).

42% percent of online game players are female.

Other genres include sci-fi MMORPGs such as Star Wars Galaxies (170,000 players) and EVE Online (130,000 players), and first person shooters (MMPFPSs), which combine first-person shooter gameplay with a large number of simultaneous players over the Internet. World War 2 Online (12,000) and PlanetSide (54,000) are just two notable games of this genre.