A preamble is an introductory and expressionary statement in a document that explains the document's purpose and underlying philosophy. When applied to the opening paragraphs of a statute, it may recite historical facts pertinent to the subject of the statute. It is distinct from the long title or enacting formula of a law.
The preamble to the United Nations Charter
The preamble to the Constitution of India
French Constitution of 27 October 1946
The Constitution of the French Republic of 27 October 1946 was the constitution of the French Fourth Republic.
Facsimile of the 1946 Constitution