"This book provides an update on recent development of crowdsourcing in terms of theoretical frame, system design principles and best practices. The editors and authors have demonstrated the use of crowdsourcing in a diversity of application areas. The book constitutes a very useful reading for academic researchers, graduate students and professionals who are interested in crowdsourcing. It also provides good references to researcher and practitioners who would like to apply crowdsourcing in different context and situations." (Gang Li and Yiqing Tu, Information Technology & Tourism, Vol. 16, 2016)