The term MMO is an acronym for the phrase, Massively Multiplayer Online Game. These most commonly are computer games in which thousands, or even millions, of players can play simultaneously. These games are played on the Internet and revolve around a single or small group of virtual worlds hosted by massive servers.
MMOs are popular largely because they enable players to cooperate and or compete with each other within the virtual world, through their unique avatar. A few characteristics of MMOs are that they typically require players to spend enormous amounts of their time playing the game, as well as promoting meaningful interaction between people through the games as they cooperate to complete tasks. Furthermore, most MMOs demand a monthly or yearly subscription fee, as a means of profit or to help maintain/develop the game. Some examples of MMOs are Second Life and World of Warcraft.