This document provides an overview of key concepts in political science including the definition of political science, the state, and the essential elements of a state. It discusses that a state requires a permanent population living in a defined territory with their own government that has sovereignty. The essential elements of a state are the people, territory, and government. It also examines theories on the origin of states such as the social contract theory which asserts that early states were formed by a voluntary compact among people to form a society and organize government.