Ideologies play a crucial role in the way we understand and shape the political world. However, no one has been able to explain the nature of ideologies themselves. In this important new book, Freeden offers a ground-breaking approach to the subject. Drawing on the political experience of Britain, France, Germany, and the USA over the last two hundred years, the author provides an in-depth examination of all the key political ideologies: liberalism, conservatism, socialism, feminism, and green political thought.