Today, we live in a post-truth era. Creating alternative realities, and making people believe fake realities become easier. Digital platforms tend to promote dramatic, sensational and emotional content that harms democracy. This book examines different aspects of the matter: rise of populist politics, impact of digital social platforms, engagement-oriented algorithms, spread of disinformation and counter-measures like fact-checking mechanism and developing digital media literacy skills. 　"Journalists, academics and civil society groups are increasingly working together to help people confront the confusion caused by the post-truth realities of digital communications, which is no longer the stuff of propaganda from the state, but comes from all sides of the internet. In this information space every fact is challenged by an alternative fact, and all of these different versions of the truth look the same online." – Aidan White