"In the twenty-first-century digital world, virtual goods are sold for real money. Digital game players happily pay for avatars, power-ups, and other game items. But behind every virtual sale, there is a virtual economy, simple or complex. In this book, Vili Lehdonvirta and Edward Castronova [...] focus on virtual economies in digital games, but also touch on serious digital currencies such as Bitcoin as well as virtual economies that emerge in social media around points, likes, and followers. The theoretical emphasis is on elementary microeconomic theory, with some discussion of behavioral economics, macroeconomics, sociology of consumption, and other social science theories relevant to economic behavior."