Property ownership: the availability of certain rules that attribute property ownership to an user who created or purchased a product.Users can build new environments: the possibility for users to build personal environment outside of the ones already available (for example, new businesses, new houses, new products, etc.).While reviewing them I have taken into account the following traits as comparison criteria for this list: Some of them are already well known for having generated buzz around them, while others might be still unknown to many of you. In this mini-guide I have taken a look at virtual worlds by reviewing some of the most popular and intriguing services available today. This situation is progressively leading to the creation of alternative Internet-based marketplaces where users showcase and exchange products whilst chatting. Moreover, many recent virtual worlds also promoted a new way of marketing content and products by integrating support for e-commerce.

Virtual worlds are nowadays equipped with social networking facilities and online collaboration tools (integrating blogs, personal homepages and sometimes VoIP), which transformed them into highly valuable tools for e-learning and distance collaboration.

However, in the past few years we witnessed the birth of numerous internet-based virtual worlds, which have started moving from the initial entertainment purpose to a completely new objective, which is likely to extend the abilities of present-day real-time collaboration systems. It is a kind of ' alternative world' that was conceived to provide a different form of entertainment both online and offline. The expression ' virtual world' usually brings up to our mind the idea of a 3D environment that typically appears similar to the real world, with real world rules such as gravity, topography, locomotion, real-time actions, and communication. This habitation usually is represented in the form of two or three-dimensional graphical representations of humanoids (or other graphical or text-based avatars).' ' A virtual world is a computer-based simulated environment intended for its users to inhabit and interact via avatars.

Cybertown virtual worlds