A virtual social world (VSW) is a virtual world built on user creativity and collaboration, thus allowing the users to define their universe, rules and objectives, as well as to create digital objects and landscapes that surround them. VSWs are sometimes referred to as "metaverses" or "real virtual worlds," because of the freedom (e.g., to generate User-Created Content (UCC)) they provide. The most popular VSW is Linden Lab's Second Life. Other examples for VSWs include : * Habbo Hotel (Finland) * Blue Mars and Twinity (United States), and * HiPiHi (China).