Nationalism is one of the most pressing of global problems, exacerbating ethnic conflicts and encouraging war. It is also influential in defining the rights of democratic citizenship, and a source of inspiration and social solidarity. A way of conceiving identities that is fundamental to the modern world, nationalism is distinct from both kinship and ethnicity. It is an international discourse that shapes domestic politics as well as relations between states. Drawing on examples from Eritrea, Yugoslavia and China to France and Germany this book clarifies the way in which national boundaries and identities became central to the modern era, how they relate to development of state power, and how a host of different social movements and government policies try to make use of them. At the same time, the author also challenges attempts to "debunk" nationalism that fail to grasp why it maintains its power and centrality in modern life.