What is democracy, and how do we measure it? What defines a high-quality democracy, and what factors increase the risk of countries sliding into dictatorship? How does democracy impact economic development, inequality, and education policy? The study of democracy, democratisation, and autocratic politics is central to comparative politics and other subfields of political science, such as international relations and public administration, as well as to disciplines like economics, sociology, and history. This comprehensive book provides an introduction to the study of democracy and autocracy. It includes chapters on defining and measuring democracy, the historical development of democracy, the causes of regime stability and change, and the developmental and other effects of democracy and autocracy. The book offers an up-to-date exploration of the important questions engaging democracy researchers. Aimed at a broad audience, including bachelor students in introductory comparative politics courses, this book offers an accessible and current overview of what research reveals about democracy and autocracy, their causes, and their consequences. Carl Henrik Knutsen (b. 1981) is Professor and Research Group Leader at the University of Oslo and a Research Professor at the Peace Research Institute Oslo. Knutsen is co-PI and Steering Committee Chair of Varieties of Democracy (V-Dem) and leads several research projects, including an ERC Consolidator Grant on autocratic politics. His work focuses on measuring democracy and dictatorship, the causes of democratisation and regime change, policy-making in dictatorships, and the economic consequences of democracy.