Second Life

Second Life is an internet-based virtual world launched in 2003, developed by Linden Research, Inc, which came to international attention via mainstream news media in late 2006 and early 2007. A downloadable client program called the Second Life Viewer enables its users, called "Residents", to interact with each other through motional avatars, providing an advanced level of a social network service combined with general aspects of a metaverse. Residents can explore, meet other Residents, socialize, participate in individual and group activities, create and trade items (virtual property) and services from one another.
Second Life is one of several virtual worlds that have been inspired by the cyberpunk literary movement, and particularly by Neal Stephenson's novel Snow Crash. The stated goal of Linden Lab is to create a world like the Metaverse described by Stephenson, a user-defined world in which people can interact, play, do business, and otherwise communicate. Second Life's virtual currency is the Linden Dollar (Linden, or L$) and is exchangeable for real world currencies in a marketplace consisting of residents, Linden Lab and real life companies.
While Second Life is sometimes referred to as a game, this description does not fit the standard definition. It does not have points, scores, winners or losers, levels, an end-strategy, or most of the other characteristics of games, though it can be thought of as a game on a more basic level because it is "played for fun".
In all, more than 9.8 million accounts have been registered, although many are inactive, some Residents have multiple accounts, and there are no reliable figures for actual long term consistent usage. Despite its prominence, Second Life has notable competitors, including There, Active Worlds, and the more "mature" themed Red Light Center.

Web 2.0

Web 2.0 is a second generation of web-based communities and hosted services, for example, social-networking sites — which aims to help sharing between users. The term gained currency following the first Web 2.0 conference in 2004. Although the term suggests a new version of the world wide web, it does not refer to an update to any technical specifications, but changes in the ways software developers and end-users use webs. According to Tim O'rielly, "Web 2.0 is the business revolution in the computer industry caused by the move to the internet as platform, and an attempt to understand the rules for success on that new platform." The phrase "Web 2.0" hints at an improved form of the World Wide Web. Technologies such as weblogs, social bookmarking, podcasts, social software.