A preamble is an introductory statement in a document that explains its purpose and underlying philosophy. It serves as a preliminary or prefatory explanation, often stating the reasons and intent behind the document, particularly in constitutions or statutes. For example, the preamble to the United States Constitution begins with "We the People" and outlines the fundamental purposes and goals of the Constitution, such as forming a more perfect union, establishing justice, and securing liberty. It does not itself grant powers or rights but provides context for the provisions that follow.