What document serves as the beginning of the U.S. Constitution?

The Preamble serves as the beginning of the U.S. Constitution, outlining the fundamental purposes and guiding principles of the document. It establishes the authority of the Constitution by beginning with "We the People," indicating that the government derives its power from the consent of the governed. The Preamble sets the tone for the Constitution by introducing key concepts such as justice, domestic tranquility, common defense, and the promotion of the general welfare. This introductory statement provides the philosophical foundation for the structure and authority of the government that follows in the main body of the Constitution.

In contrast, while the Bill of Rights is crucial for enumerating individual freedoms and protections, it is an amendment that follows the original Constitution. The Articles of Confederation served as the first governing document of the United States but were eventually deemed ineffective and replaced by the Constitution. The Declaration of Independence, although vital for announcing the colonies' separation from British rule, is a distinct document that predates the Constitution and does not serve as its beginning.