This volume is the first focused effort to compile state-of-the-art research and address future directions of UGC. It explains how to collect, index, and analyze UGC to uncover social trends and user habits. The book describes how to mine various media, including social annotation, music information retrieval, and networks, and discusses the mining and searching of different types of UGC, such as Wikis and blogs. It also presents many applications of UGC, including the use of UGC to answer questions and summarize information.