A monarchy is a country that is ruled by a monarch such as a king or queen ruling a kingdom or empire. Constitutional monarchy is limited by a constitution, but in an absolute monarchy the monarch has unlimited power.
A dictatorship is a form of government in which a person or a small group rules with almost unlimited power.
A theocracy is a government or country that is ruled by someone who has the religious authority or divine right.
An oligarchy is a small group of people having control over a country.
A democracy is a form of government where people rule, either directly or through elected representatives.