In order for American government to work, cooperation among the three branches is necessary. The nation's chief executive, the president, is the head of the executive branch, who also acts as head of state and Commander-in-Chief of the armed forces. The President is responsible for implementing and enforcing the laws written by Congress and, to that end, appoints the heads of the federal agencies, including the Cabinet. The Vice President is also part of the Executive Branch, ready to assume the Presidency should the need arise.
In Article II of the Constitution, the president's qualifications and powers are detailed. In order to be considered for the office, a presidential candidate must be at least 35 years old, a natural-born U.S. citizen, and have at least 14 years of residence in the United States.
The president and vice president serve for a term of four years and can be re-elected to a second term. Franklin Delano Roosevelt was the only president to be elected more than twice. He won the presidency four times but died shortly into his last term. The Twenty-second Amendment to the Constitution was passed in 1951, limiting a president to two terms.