The Federalist is a collection of 85 essays written by Alexander Hamilton, James Madison, and John Jay in the late 18th century. These essays were published to promote the ratification of the United States Constitution and explain the principles behind the new government structure. The essays address various topics, including the need for a strong central government, the separation of powers, and the protection of individual rights. Together, they provide insight into the framers' intentions and the political philosophy that shaped the early United States.