This introductory chapter provides an overview of political theory. Political theory is the study of whether and what political institutions, practices, and forms of organization can be justified, how they ought to be arranged, and the decisions they ought to make. This is normative political theory. Normative theories are action-guiding, and so are theories about what we ought to do. There are two important things to remember when making claims in political theory. One is that moral and political values are relative to specific cultures in specific times and places, and so there is no universal truth about such matters. The second is that such values are radically subjective: individuals set their own moral compass and can choose how to live as they please. We should be clear about which of these positions we are invoking if we are sceptical of universal normative claims.