The document known as the foundation of U.S. government is the Constitution, ratified in 1788. The Constitution established the framework for the federal government, outlining the separation of powers among the executive, legislative, and judicial branches. It also enumerates the rights of citizens, providing a system of checks and balances to prevent any one branch from becoming too powerful. The Bill of Rights, added in 1791, further protects individual liberties. The Constitution has been pivotal in shaping American democracy, guiding the nation through numerous changes and challenges while remaining a living document through amendments and interpretations.