The US is governed under what is called a Constitutional Republic. There are three separate and co-equal branches of government: Judicial, Legislative, and Executive. These branches are vested with power by the US Constitution. This is the starting point for you. I don't have the time or desire to write a detailed explanation. Important Note: The USA is NOT a democracy. It never has been. Many think it is, but it is not. Democracy is mob rule.

To add to Jerry's answer: * The Legislative branch (the Senate and the House) makes the law. Senators and congressmen are elected directly by the people of their state. * The Executive branch (the President) signs the law. The President does NOT get elected by the people. In the basic terms, the people in a state vote for a group of representatives, who promise to elect a particular president. This happens in November, and then this group of representatives vote to elect the President in January. * The Judicial branch (the Court) interprets the law. The president nominates a Supreme Court Justice. The congress then approves the Justice, who has the job for life.

The USA is made up of federation of states and includes a number of dependancies. Citizens, via a collegiate voting system they can choose members of the Senate house and the House of Congress plus the President. They also have The Supreme Court who are put in place by the other three "players". These four "players" then make up the Federal government. Powers are controlled either by the Federal State or the State, what there powers are and who is responsible for what can be a matter for discussion. But to be fair I have no idea if this is completely true. :-)

Note to Bill: The members of the Supreme Court, called justices, are selected by the president and 'ratified' by the Congress. You did a pretty good job. Most Americans could not name a single branch of government let alone the theory of governance.

they have the congress ,the president , and the courts