Which country changed sides a year after world war 1 began

The executive branch is responsible for implementing the laws that are created by the legislative branch (the Senate and House of Representatives).  The head of the executive branch is the President of the United States.  His role includes acting as the Commander-in-Chief of the Armed Forces.  If the President is unable to serve out his term (due to death, impeachment, or resignation), the Vice-President will take over, making him another important member of the executive branch.

In addition to the President and Vice-President, the executive branch includes the heads of the executive departments (Department of State, Department of Defense, etc.).  The heads of these departments are called Secretaries and they serve as members of the President's Cabinet