This book provides a comprehensive overview over the models of contemporary democracy, its social, cultural, economic and political prerequisites, empirically existing varieties, and the two major challenges - globalization and mediatization - confronting established democracies today. As the boundaries of the national political communities increasingly dissolve, democracy as we know it is put into question. Similarly, as the role of the media in politics increases, the way established democracies function is being transformed. The book covers the transformation of established democracies, democracy's global expansion into new countries, as well as its spread into supranational polities such as the European Union. It confronts head on democracy's constantly changing nature; its diversity of institutions and practices; its repeated need to respond to exogenous challenges and, most importantly, its perpetually unsatisfactory quest to make 'real-existing democracy' conform better to 'potentially ideal democracy.'