The Preamble of the U.S. Constitution serves as an introduction that outlines the core purposes and guiding principles of the document. It establishes the intent to form a more perfect union, promote justice, ensure domestic tranquility, provide for the common defense, and secure the blessings of liberty. This foundational text articulates the vision of governance and unity, reflecting the democratic ideals that the framers sought to achieve, thereby setting the tone for American democracy.