Digital Museums in 3D Virtual Environment Second, the social media, also known as social networking approach, has been potentially en- gaged in the museum context of which purpose is to foster relationship within the museum commu- nity as successfully as wikis, Flickr, and Youtube, Blogger, and Myspace that incorporate Web 2.0. Digital museums can merge those applications and services for emphasizing the community collabo- ration and communication. Moreover, the venue of visitors' experiences has shifted from exclusively on site to inclusion of interactions taking place elsewhere outside of the control of the museum as found in those social media sites as described in many researches (Alexander, Burnette, Dark, Hart, Rossi & Minor, 2008; Baker, Hoover & Sherman, 2009; Oates, 2008; Watrall & Siarto, 2007; Caruth & Bernstein, 2007). Third, personalization is a hot issue in many applications that thousands of researches have investigated. Also, digital museums face diverse target groups, reaching from young to old, with varying Internet usage levels, learning styles and preferences. The personalization feature is to serve these diverse needs efficiently so that the digital museums can maximize the visitors' satisfactory as well as optimize the visiting total time. Three projects are briefly explained herein. First, a Web- based personalized content of a museum includes two basic features: target group profiles and user customization (). Second, an adaptive museum gal- lery in SL is a prototype of how the virtual world can be personalized to match the learning skill of each individual visitor, ranging from the beginner to the professionals (Oberlander, Karakatsiotis & Isard, 2008). Third, an interactive mobile guide is used in the physical museum space (Benelli, Bianchi, Marti, Sennati & Not, 1999), for example, the visitors can search the information on artworks they want to see and, then, the guide will show the way to reach them. COMPARISONS OF 3D VIRTUAL ENVIRONMENTS The use of 3D virtual environments has enor- mous potential in museums, which allows a user to interact with a 3D simulated environment of either the physical world or an imaginary world. The first use was in 1994 when the past Dudley castle in England was displayed on a screen and navigated through from a superficial point of view as the castle was in 1550 (Boland & Johnson, 1997). This is the most common application of museums in the virtual world. Then came the CAVE system and the virtual theatre that are bet- ter than a screen as they can reproduce the actual atmosphere at given sites with a greater level of realism such as the Dunhuang CAVEs (Weiden- hausen & Stricker, 2000). However, the users in the above environments only play a passive role as an observer. Alternatively, an environment where its users can have more active role is the Multi-User Virtual Environment (MUVE), that has the social-community feature similar to that in the Web 2.0. MUVEs, sometimes called virtual worlds, pro- vide free interactions among the users. In MUVE, there are no strictly defined tasks, and its users, also called residents, have no pre-defined objectives. Presently, major MUVEs include Second Life (SL), Active World, Blue Mars, Cobalt, Wonder world, Digital Spaces, and Modulla. Compared to the other virtual worlds, SL is the largest virtual world bursting with opportunities in areas such as collaborative learning, legal practice, and cor- porate connections, and having the total number of residents more than nine millions as reported in its official website (August, 2009). In addition, SL provides a wide spectrum of on-line activities, including arts, science, sports, and education. Within it, the residents can explore, meet other residents, socialize, and participate in many kinds of activities. Several organizations in RL have opened their branches in SL that involve 716