Virtual world

A virtual world is generally described as a computer-simulated environment that many people share over a network at the same time, that keeps existing when individual users log off, and in which each user is represented by an avatar that can act in the environment and communicate with others. Researchers have proposed several competing definitions. In the first issue of the Journal of Virtual Worlds Research in 2008, Mark W. Bell described a virtual world as "a synchronous, persistent network of people, represented as avatars, facilitated by networked computers".

Many early virtual worlds ran on ordinary computers rather than virtual reality hardware. The text-based game MUD was written at the University of Essex from 1978, Lucasfilm Games began building the graphical online world Habitat in 1985, and Second Life opened to the public in 2003. Social VR platforms such as VRChat and Horizon Worlds carry the same model onto head-mounted displays, and the idea of linking many virtual worlds into one network is the basis of the broader Metaverse concept.

This article covers virtual worlds as a general concept and their relationship to VR and AR. The shared-workspace research tradition is covered in Collaborative virtual environment, present-day headset platforms in Social VR, and the vision of an interconnected network of worlds in Metaverse.

Reviewed 6 October 2026. Checked every definition quote, history date and VR platform claim against Bell 2008, Schroeder 2008, Girvan 2013/2018, Nevelsteen 2018, Castronova 2001, Bartle, Morningstar and Farmer, Crossref/Semantic Scholar paper metadata, and the cited TechCrunch, Road to VR, UploadVR, Meta, Steam and Frontiers pages. About review dates.

Definitions

There is no single agreed definition. Bell opened his 2008 essay by noting that the term "is used in different ways at different times by academics, industry professionals and the media", and built his own definition by combining three earlier ones. Ten years later, Carina Girvan wrote in Educational Technology Research and Development that there had been "little development of the term" since 2008, that new terms were used sometimes to classify types of virtual world and sometimes as synonyms, and that a "resurgence of interest in the potential of virtual reality" had further muddied "the conceptual waters".

Author and year	Definition or defining features
Edward Castronova (2001)	A computer program with three defining features: interactivity (remote, simultaneous access by a large number of people, with one person's inputs affecting the results of others), physicality (an interface simulating a first-person physical environment, generally ruled by the natural laws of Earth and marked by scarcity) and persistence
Richard Bartle (2003), as quoted by Bell	A world is "an environment that its inhabitants regard as being self-contained"
Raph Koster (2004), as quoted by Bell	"a spatially based depiction of a persistent virtual environment, which can be experienced by numerous participants at once, who are represented within the space by avatars"
Edward Castronova (2004), as quoted by Bell	"crafted places inside computers that are designed to accommodate large numbers of people"
Mark W. Bell (2008)	"A synchronous, persistent network of people, represented as avatars, facilitated by networked computers"
Ralph Schroeder (2008)	"persistent virtual environments in which people experience others as being there with them", where they can also interact with them
Carina Girvan (2013 technical report)	"A persistent, simulated and immersive environment, facilitated by networked computers, providing multiple users with avatars and communication tools with which to act and interact in-world and in real-time"
Kim J. L. Nevelsteen (2018)	A simulated environment in which many agents (zero or more humans, each represented by an avatar, and software agents) can interact with each other and the environment in a "real-time shared spatiotemporal non-pausable virtual environment" that forms "one persistent shard"

Common elements

Bell explained each term in his definition. Synchronous means that activity happens in a shared common time; a turn-based space, he wrote, "is more like a delayed email thread than a world". Persistent means that "a virtual world cannot be paused" and keeps functioning after a participant leaves, which separates it from games such as Pac-Man. An avatar is "any digital representation (graphical or textual), beyond a simple label or name, that has agency", so a textual description of a character in MUD-1 counts, while a Facebook profile does not. Networked computers separate a virtual world from a well-managed game of Dungeons & Dragons, since no pencil-and-paper game could manage and store all of a world's objects, environments, interactions and transactions indefinitely.

Applying these criteria, Bell counted MUD-1, Neverwinter Nights, Second Life and World of Warcraft as virtual worlds. He excluded Mario Kart, which has synchronous multiplayer but no persistence, and social networking sites, which have persistence but "no sense of synchronous environment". Castronova described persistence in similar terms in 2001: the program "continues to run whether anyone is using it or not; it remembers the location of people and things, as well as the ownership of objects".

Disagreements

The definitions disagree on whether text worlds and single-user simulations qualify. Schroeder, who had defined virtual environments and virtual reality technology in 1996 as "a computer-generated display that allows or compels the user (or users) to have a sense of being present in an environment other than the one they are actually in, and to interact with that environment", argued that the sensory experience of "being there" must be part of the definition, because without it "anything goes": books, dreams and text-based MUDs could all be called virtual worlds. He noted that the term had been applied to persistent online social spaces, and treated online games as a subset of virtual worlds in which the activity revolves around gaming. Bell, by contrast, explicitly included the text-based MUD-1.

Girvan's 2013 definition came from a systematic review of 88 peer-reviewed articles in the educational literature. She noted that different authors had labelled the same platform, Second Life, a virtual world, a multi-user virtual environment (MUVE), an immersive virtual world, a social virtual world and a virtual environment. Nevelsteen derived his 2018 definition by analysing 26 sample technologies with grounded theory. Unlike Bell and Girvan, his definition does not require multiple users or networking, "allowing for virtual worlds that are pure simulations"; he also criticised Girvan's literature sample as heavily weighted toward Second Life, with 47 of 68 surveyed articles referring to it.

History

Text-based worlds

According to Richard Bartle, the first version of MUD was written by Roy Trubshaw in MACRO-10 assembly language for a DECsystem-10 at the University of Essex in autumn 1978. It was "little more than a series of inter-connected locations where you could move and chat"; Trubshaw rewrote it, and when he left Essex, Bartle, who had been helping with the game design, took over full control. Bartle and Trubshaw ask that it be described as created and written by both of them. In spring 1980 the first external players logged in over an experimental packet-switching link between Essex and the ARPANET, and the original game was later licensed to CompuServe, where it ran under the name "British Legends". Bell described Bartle as a "creator of text-based virtual worlds in the 1970s and 1980s".

Habitat

Lucasfilm Games began building Habitat in 1985 for QuantumLink, an online service then limited to owners of the Commodore 64, with a backend on Stratus fault-tolerant minicomputers. Chip Morningstar and F. Randall Farmer, who developed it, described it as "arguably one of the first attempts to create a very large scale commercial multi-user virtual environment". Players appeared as animated figures the developers called "Avatars", talked by typing text that appeared above their heads in cartoon-style "word balloons", and moved between discrete "regions"; in its prime the prototype world had around 20,000 regions. Morningstar and Farmer wrote that the system could support "a population of thousands of users in a single shared cyberspace".

The pilot operations eventually ended and that system was shut down. When the authors wrote their account, Habitat's North American incarnation, QuantumLink's "Club Caribe", had been operating for almost two years with a population of some 15,000 participants, and a more advanced version, Fujitsu Habitat, had begun pilot operations in Japan on NIFtyServe for the FM Towns computer. The authors summarized their "essential lesson" as "a cyberspace is defined more by the interactions among the actors within it than by the technology with which it is implemented".

Graphical 3D worlds

Castronova called Meridian 59, begun in 1995 by the Microsoft interns Andrew and Chris Kirmse, "the game that started the recent explosion" of virtual worlds, and described the form as a combination of the 3D environments of games like Tomb Raider with the chat-based social systems of MUDs. According to the Active Worlds community wiki, the Active Worlds browser was officially released on 28 June 1995 as AlphaWorld, a project by Ron Britvich.

Verant Interactive, part of Sony, launched EverQuest on 16 March 1999 on five servers in San Diego. Castronova, an economist, spent April to September 2001 in its world of Norrath and estimated that players earned a nominal wage of about US$3.42 an hour and that Norrath's output put its GNP per capita "somewhere between that of Russia and Bulgaria".

Linden Lab opened Second Life to the public on 23 June 2003. Three years later, TechCrunch reported Linden Lab's figures showing the Second Life economy on pace for US$60 million in user-to-user transactions in 2006.

From virtual worlds to the metaverse

In a 2013 survey in ACM Computing Surveys, John David N. Dionisio, William G. Burns III and Richard Gilbert argued that moving "from a set of independent virtual worlds to an integrated network of 3D virtual worlds or Metaverse" depended on progress in four areas: immersive realism, ubiquity of access and identity, interoperability and scalability. Stylianos Mystakidis wrote in 2022 that the metaverse's "first iteration was a web of virtual worlds where avatars were able to teleport among them", and that its contemporary iteration features "social, immersive VR platforms compatible with massive multiplayer online video games, open game worlds and AR collaborative spaces".

Virtual worlds and virtual reality

Separate traditions

Early virtual worlds and VR research developed largely apart. Writing about Habitat in 1990, Morningstar and Farmer called the enthusiasm around "DataGloves, head-mounted displays, special-purpose rendering engines, and so on" "both excessive and somewhat misplaced", and argued that the defining characteristic of cyberspace "is the shared virtual environment, not the display technology used to transport users into that environment". In their view, such a cyberspace was feasible "if you can live without head-mounted displays and other expensive graphics hardware". Multi-user VR existed in parallel: Liu and Steed note that some of the earliest commercial VR systems of the late 1980s and early 1990s supported collaboration, citing Reality Built for Two from VPL Research.

Nevelsteen argued that the device used to reach a virtual world "does not and should not determine its worldliness", so that a text MUD on a smartphone is still a MUD, and named head-mounted displays as one possible way to access future worlds. He cited Dionisio and colleagues' statement that virtual worlds "constitute a subset of virtual reality applications", since only some VR environments meet the definition of a world.

Adapting existing worlds to headsets

When the Oculus Rift developer kits appeared, Linden Lab added Rift support to Second Life. In October 2014 Road to VR reported that the Second Life viewer supported the Oculus Rift DK2 through a "Toggle HMD Mode" option. In July 2016 Linden Lab suspended official support for the consumer Rift, citing "inherent limitations with SL" that made adequate VR performance difficult, and said it was building a separate platform optimized for VR, Sansar. Sansar launched in beta with support for both VR and desktop use, but according to TechCrunch the majority of its users were desktop-based; in March 2020 Linden Lab sold the Sansar assets to Wookey Search Technologies.

Social VR worlds

Multi-user platforms designed around headsets are studied under the name social VR. Liu and Steed use the term for "immersive systems that prioritize and focus on the in-environment communication", and compared six of them on the Oculus Quest in 2021: VRChat, Rec Room, AltspaceVR, Bigscreen, Spatial and Mozilla Hubs. VRChat, where users create their own worlds and avatars, lists 1 February 2017 as its release date on Steam. Meta opened Horizon Worlds, which it called "a social VR experience where you can create and explore together", to everyone aged 18 or over in the United States and Canada on 9 December 2021.

Some of these platforms have since closed or reduced their VR focus. In March 2026 Rec Room announced that it would close on 1 June 2026, after reaching 150 million users according to UploadVR; the company said "our costs always ended up overwhelming the revenue we brought in". In March 2026 Meta CTO Andrew Bosworth said the company would "keep Horizon Worlds working in VR for existing games", while development of its new Horizon Engine would concentrate on mobile phones.

Virtual worlds and mixed reality

Nevelsteen applied his definition to mixed reality using Paul Milgram and Herman Colquhoun's continuum between the virtual and the physical. If parts of a virtual world, such as its time, space or agents, are mapped to physical counterparts, the world falls between the purely virtual and the physical. By that test, World of Warcraft is technically a mixed world, because its day and night schedule follows the computer's real-world system time. He also concluded that, since the Internet already mixes the physical and the virtual through video conferencing, live webcams and teleoperation, a future metaverse "will be necessarily mixed as well".

Research

Virtual worlds have been studied in economics, education and human-computer interaction. Castronova's 2001 working paper on EverQuest treated Norrath as an economy with its own wages, prices and currency exchange rates. Girvan's reviews drew on research into virtual worlds in education.

Research on headset-based worlds has focused on social interaction and embodiment. In a CHI 2019 paper, Joshua McVeigh-Schultz, Anya Kolesnichenko and Katherine Isbister interviewed creators of Rec Room, High Fidelity, VRChat, Mozilla Hubs, AltspaceVR, Anyland and Facebook Spaces, and identified four design considerations: aesthetics of place, embodied affordances, social mechanics, and tactics for shaping social norms and mitigating harassment. Guo Freeman and Divine Maloney interviewed 30 users about how people present themselves and perceive others in social VR, which they described as 3D spaces where multiple users interact through head-mounted displays and full-body tracked avatars. Liu and Steed's guided group walkthrough of six social VR platforms found none of the usability problems "severe enough to prevent progress or cause the termination of a session".

See also

• Metaverse
• Social VR
• Collaborative virtual environment
• Avatar
• VRMMO
• Mirror world
• Presence
• Proteus effect