There are four main types of governments: monarchy, oligarchy, direct democracy, and representative democracy. A monarchy has a single hereditary head of state, and was once very common but now exists in over 40 countries. An oligarchy concentrates political power among a small elite group, often based on wealth, military strength, or family ties. A direct democracy involves all members of society having an equal say through referendums. A representative democracy exists in countries like the US, where citizens elect representatives to make laws on their behalf due to the large population size.