There are three main forms of government: autocracy, oligarchy, and democracy. Autocracy is rule by one person, like a dictator. Oligarchy is rule by a small group, like a royal family or military leaders. Democracy gives power to citizens through voting, and there are two main types - presidential democracy which separates powers, and parliamentary democracy where parliament selects the prime minister. Constitutional monarchies also exist where a monarch serves as head of state but elected leaders govern.