In computer gaming, a MUD (Multi-User Dungeon, Domain or Dimension) is a multi-player computer game that combines elements of role-playing games, hack an slash style computer games and social chat rooms. Typically running on an Internet server or bulletin board system, the game is usually text-driven, where players read descriptions of rooms, objects, events, other characters, and computer-controlled creatures or non-player characters (NPCs) in a virtual world. Players usually interact with each other and the surroundings by typing commands that resemble a natural language, usually English. Arguably, modern graphics-based massively multiplayer online role-playing games (MMORPGs), such as World of Warcraft, and social avatar virtual worlds such as Second Life can be considered MUD variants.