This encyclopaedia, first published in hardback as the "Blackwell Encyclopaedia of Political Institutions", elucidates the main terms and concepts employed in the study of politics. This edition has been selectively revised and updated. It analyzes the ideas used in the study of political institutions, the main forms of political organization (for example, democracy, oligarchy, dictatorship) and the main types of political community (for example, confederation, empire). The encyclopaedia also contains entries on the main political schools of thought (socialist, liberal, conservative) and leading political scientists of the past (including Bentham, Bagehot, Ostrogorski).