A virtual economy (or sometimes synthetic economy) is an emergent economy existing in a virtual persistent world, usually exchanging virtual goods in the context of an Internet game. People enter these virtual economies for recreation and entertainment rather than necessity, which means that virtual economies lack the aspects of a real economy that are not considered to be "fun" (for instance, avatars in a virtual economy often do not need to buy food in order to survive, and usually do not have any biological needs at all). However, some people do interact with virtual economies for "real" economic benefit.
Despite primarily dealing with in-game currencies, this term also encompasses the selling of virtual currency for real money.
Virtual economies are observed in MUDs and massively multi player online role-playing games (MMORPGs). The largest virtual economies are found in MMORPGs. Virtual economies also exist in life simulation games which may have taken the most radical steps toward linking a virtual economy with the real world. This can be seen, for example, in Second Life's recognition of intellectual property rights for assets created "in-world" by subscribers, and its laissez-faire policy on the buying and selling of Linden Dollars (the world's official currency) for real money on third party websites. Virtual economies can also exist in browser-based Internet games where "real" money can be spent and user-created shops opened, or as a kind of emergent gameplay.
A virtual world or massively multiplayer online world (MMOW) is a computer-based simulated environment populated by many users who can create a personal avatar, and simultaneously and independently explore the virtual world, participate in its activities and communicate with others. These avatars can be textual, two or three-dimensional graphical representations, or live video avatars with auditory and touch sensations. In general, virtual worlds allow for multiple users.
The user accesses a computer-simulated world which presents perceptual stimuli to the user, who in turn can manipulate elements of the modeled world and thus experience a degree of presence. Such modeled worlds and their rules may draw from the reality or fantasy worlds. Example rules are gravity, topography, locomotion, real-time actions, and communication. Communication between users can range from text, graphical icons, visual gesture, sound, and rarely, forms using touch, voice command, and balance senses.