This book introduces the readers to recent research concerning diffusion in social networks and attempts bring together disparate lines of work on the topic from multiple fields. The availability of large social network datasets over nearly the past two decades have made it possible to explore network diffusion like never before. Having said that, the materials covered in this book is not limited to the online platforms, but rather are thought to be applicable to social networks from a variety of domains. Similar to other subjects in social network analysis, information diffusion has its roots in multiple field of study: biologists and physicists have done research in the field by studying evolutionary dynamics  and disease propagation models ; economist and Nobel Laureate Thomas Schelling introduced the idea of “tipping points” which now has become mainstream ; concurrently Mark Granovetter studied these ideas from a sociological perspective . However, it wasn’t until Kempe et al. article  in 2003 that information diffusion became a significant line of research in computer science.