There are three main types of governments: autocracy, oligarchy, and democracy. Autocracy is rule by one person, like a dictator, while oligarchy involves rule by a small group. Democracy gives citizens a say through voting and most modern democracies are republics where citizens elect representatives. Democracies can be presidential, with citizens voting directly for the head of state and government, or parliamentary, where the legislature selects the head of government. Governments provide structure, laws, services, and defense for their countries. Power is shared in different ways between federal, unitary, and confederate systems.