US government is based on three principles: inherent rights, self government and separation of powers into legislative, executive and judicial. Legislative power is exercised by Congress, executive power is exercised by President and judicial power is exercised by Federal court judges. No branch has more power than the other through a system of checks and balances.
Congress consists of two houses: Senate and House of Representatives. In the Senate there are 100 members elected every two years from each state regardless of its size and population. In the House of Representatives there are 435 members elected every two years from state congressional districts. The Senate is more powerful than the House. Every new law must have the approval of both houses of Congress and the signature of the president.
The president is head of state, of the armed forces and of the federal government. For this the president represents the country abroad, he can send the military on missions and he appoints all important officials, including the members of the cabinet. The president is elected from the people every four years and he can serve two 4-years terms.
It was agreed that no branch would have more power than the other and it is possible through the system of checks and balances. In this system each branch operates independently of the others but there are built in “checks and balances” to prevent tyrannous concentration of power in any one branch. For example, the President can veto bills approved by Congress and the President nominates individuals to serve in the Federal judiciary; the Supreme Court can declare a law enacted by Congress or an action by the President unconstitutional; and Congress can impeach the President and Federal court judges.