What is defined as the introductory statement of a formal document outlining its purpose?

The term that refers to the introductory statement of a formal document, which outlines its purpose, is the preamble. A preamble serves as an introduction that sets the stage for the content that follows. It typically provides context, explains the intentions behind the document, and outlines the foundational principles that guide the more detailed content within the formal work. This is seen in significant documents such as the Constitution of the United States, where the preamble summarizes the document's aims and objectives.

In contrast, a conclusion generally serves to summarize and wrap up the content rather than introduce it. An introduction may sound similar, but it often refers to the opening section of a document that begins to delve into the main topics, rather than specifically framing the purpose as a preamble does. A summary typically recaps the main ideas or arguments presented in a document, rather than providing the foundational purpose that a preamble offers. Thus, the selection of preamble is accurate in defining this specific aspect of formal documentation.