What three types of government does Aristotle identify?

Aristotle identifies three legitimate types of government: monarchy (rule by one), aristocracy (rule by a few), and polity (rule by the many), which he considers a form of constitutional government. Each of these can devolve into their corrupt forms: tyranny (the corrupted form of monarchy), oligarchy (the corrupted form of aristocracy), and democracy (the corrupted form of polity). Aristotle emphasizes the importance of the common good in distinguishing between the legitimate and corrupt forms of government.