The governmental system used by the United States is a representative democracy.
Representative democracy is based on two major principles.
These two principles are the separation of powers and federalism. These three branches are given specific functions by the Constitution which legitimates their power. Federalism refers to the divided authority of power between the national, state, and local levels of government. The executive branch of government is headed by the president, who is popularly elected every four years. The legislative branch is divided into the House and the Senate.