Separation of Powers: The government is separated into 3 different branches. The Legislative Branch consists of the Congress. The Executive Branch consists of the President and his cabinet. The Judicial Branch consists of the Federal Courts. It is separated into 3 different branches in order to keep one branch from having supreme power of the other.
Ex: All the branches depend on each other but the job of the Executive branch is to basically enforce the Constitution. It is also supposed to keep track of both the Legislative and Judicial branches.