Book excerpt: Due to the advancement of the Internet, online communities are gaining increasing importance in the research community. Presented from a user's perspective, this book explores the diverse application areas of social computing and online communities. A significant portion of the text focuses on real-world case studies in which user behaviors, social mechanisms, and technological issues are investigated. Drawing from computer science, information systems, and social science, the book takes a multidisciplinary approach to evaluate virtual communities. It is useful for those who construct, moderate, and maintain online communities.