Online communities are computer-mediated spaces built to bring together geographically dispersed like-minded individuals to form social networks for exchanging information, sharing knowledge, doing transactions, developing relationship, performing social activities and enjoying entertainment.The long-term sustainability of an online community depends on whether users are willing to continue using it. The purpose of this book is to investigate why users in China continuance using virtual communities for various purposes, including general participation, information/knowledge seeking, and information/knowledge sharing.