The Unwritten Constitution includes the ability to create cabinets, the promise of the Electoral College, term limits for the presidents and the creation of Congressional committees and political parties. Although these and other customs are common knowledge, contrary to what many Americans believe, they are not official laws.
Cabinets were first created by the Washington administration, and cabinet leaders advised the President on important national matters. The Electoral College was its own entity when it first came into existence, and term limits for presidents became enforced after President Franklin D. Roosevelt stayed in office for over a decade.
There is no mention of political parties in the Constitution, although they are something Americans depend on when it comes time to choose their elected officials. Congressional committees came into existence to help make recommendations on bills, but they are not outlined in the Constitution.