There are three branches in the American system of government: the Legislative, the Executive, and the Judicative.
In the Legislative, the laws are made. New laws need long time till they become legal laws: First a member of the senate (one third elected every two years for six years by the people) or a member of the House of Representatives (elected every two years by the people, too) has to make a suggestion for a law. Then a committee has to accept the bill. If then there is a majority of senators or members of the House of Representatives, the bill is passed on the other house of Congress. Then the other house has to form a comittee, and, if it is passed through the commitee, the majority of members of the other house has to accept it. Finally the bill is passed on the President. he can either accept the law or veto it.
In the Executive the Administration enforces the laws, that is, they make sure that the laws are carried out. In the Administration there are the President and Vice President (elected by the people for four years) and the Cabinet. The President can appoint and dismiss members of the Cabinet, and he can appoint judges in the Judicative.
In the Judicative the laws are interpreted. There are one chief justice and eight other justices.