A virtual world (also known as a virtual space) is a computer-simulated environment that can be populated by many users who can create a personal avatar and explore the virtual world, participate in its activities, and communicate with others simultaneously and independently. These avatars can be textual, graphical, or live video representations with auditory and tactile sensations. Mirror worlds and virtual worlds are closely related. In a virtual world, the user enters a computer-simulated world that provides perceptual stimuli to the user, who can then manipulate elements of the modeled world to experience a sense of presence. These modeled worlds and their rules may be inspired by reality or fantasy worlds. Gravity, topography, locomotion, real-time actions, and communication are some examples of rules. Text, graphical icons, visual gesture, sound, and, on rare occasions, forms using touch, voice command, and balance senses can all be used to communicate between users.
MMO games depict a wide range of worlds, including those based on reality, science fiction, super heroes, sports, horror, and historical settings. The majority of MMORPGs feature real-time actions and communication. Players design a character who travels between buildings, towns, and worlds for business or pleasure. The majority of communication is textual, but real-time voice communication is also possible. The mode of communication used can have a significant impact on the game experience of the players. To discuss individual virtual worlds, media studies professor Edward Castronova used the term “synthetic worlds,” but this term has not been widely adopted. Virtual worlds are not limited to games, but can also include computer conferencing and text-based chat rooms, depending on the level of immediacy presented.
Unlike most video games, which are typically navigated using a variety of free-ranging human interface devices (HIDs), virtual worlds are typically navigated (as of 2009) using HIDs that are designed and oriented around flat, 2-dimensional graphical user interfaces; because most comparatively inexpensive computer mice are manufactured and distributed for 2-dimensional UI navigation, the lack of 3D-capable HID usage among most virtual world users is likely due to both a lack of penetration and a lack of penetration. Even users who do use HIDs with features like six degrees of freedom must frequently switch between separate 3D and 2D devices to navigate their respective designed interfaces.
Like video gamers, some users of virtual world clients may struggle with the requirement of proper graphics hardware (such as the more advanced graphics processing units distributed by Nvidia and AMD) for the purpose of reducing the frequency of less-than-fluid graphics instances in virtual world navigation. However, because of this, an increasing number of virtual world engines, particularly those aimed at children, are entirely browser-based, requiring no software downloads or specialized computer hardware. Whyville.net was the first virtual world of this type, launched in 1999 by Numedeon Inc., which obtained an early patent for its browser-based implementation.