"What happens when players of all ages, sexes, and intelligences collide head-on? It's hard to treat World of Warcraft like any other game. With nine million players worldwide and growing, it's a phenomenon. The average server, or instance of the game, has a population of thousands online at any one time. With so many people packed into the same world, cooperation offers a clear advantage to those who seek virtual success.
When a new server is first opened, players quickly move to form social groups, like nervous sixth graders before the first day of recess. While some massively multiplayer games place less of an emphasis on group play, the development team at Blizzard have perfected a guild-dependent system. Much of the higher-end dungeons in the game were designed to require a high degree of skill and coordination that cannot be achieved through casual "pick up" games. Players are all but required to band together in order to continue "raiding" past a certain point."