A preamble is an introductory statement that explains the purpose or reasoning behind a document. The most famous preamble in American history begins the U.S. Constitution with the words “We the People” and explains why the Founders created the Constitution: to form a better union, establish justice, ensure peace, and secure liberty.

Think of a preamble as the “why” before the “what.” Before a document lists its rules or requirements, the preamble explains the thinking behind them. Your school's student handbook might have a preamble explaining that its rules exist to create a safe, respectful learning environment. A treaty between nations might include a preamble describing their shared goals for peace.

A preamble walks ahead of the main text, preparing readers for what follows. While the detailed rules and requirements matter, the preamble reveals the values and intentions that shaped them. When the Constitutional Convention debated specifics for months, Gouverneur Morris wrote a preamble that expressed their highest hopes in just 52 words. That preamble still reminds Americans today what their government is meant to accomplish.