The Founding Fathers, the framers of the Constitution, wanted to form a government that did not allow one person to have too much control. With this in mind, the framers wrote the Constitution to provide for a separation of powers, or three separate branches of government. Each has its own responsibilities and at the same time they work together to make the country run smoothly and to assure that the rights of citizens are not ignored or disallowed. This is done through checks and balances. A branch may use its powers to check the powers of the other two in order to maintain a balance of power among the three branches of government.
Legislative - Makes Laws
The Senate has 100 elected senators total; 2 senators per state. Each senator serves a 6 year term.
House of Representatives
The House has 435 elected representatives total; representatives are based on each state's population. Each representative serves a 2 year term and may be re-elected.
Executive - Carries Out Laws
The president is the head of state, head of the U.S. government and the commander-in-chief of the U.S. military.
The vice president not only supports the president, but also acts as the presiding officer of the senate.
The Cabinet members are nominated by the president and must be approved by the Senate (with at least 51 votes). They serve as advisors and heads of various departments and agencies.
Judicial - Evaluates Laws
The judicial branch of government is made up of the court system.
The Supreme Court is the highest court in the country. The 9 justices are nominated by the president and must be approved by the Senate (with at least 51 votes).
Other Federal Courts
There are lower Federal courts but they were not created by the Constitution. Congress deemed them necessary and established them using power granted from the Constitution.
Courtesy of Ben's Guide