This book is about the role that social media plays in the lives of individuals, societies, economies and polities. It therefore takes in a wide view of the emergent and changing impacts of social media platforms, and social media practices. As a consequence, it examines social media use through various intellectual and scholarly traditions --psychology, sociology, cultural studies, economics, and (national and global) politics – but it is primarily situated in the field of media and communications studies. As such, it frames its analysis of social media impacts using media studies concepts and terminology, and places media texts, forms, industries and agents (producers, audiences and other users) at the centre of each thematic chapter.