What is an executive summary?

an executive summary is a short document or section of a document.

An executive summary, or management summary, is a short document or section of a document, produced for business purposes, that summarizes a longer report or proposal or a group of related reports in such a way that readers can rapidly become acquainted with a large body of material without having to read it all. It usually contains a brief statement of the problem or proposal covered in the major document (s), background information, concise analysis and main conclusions. It is intended as an aid to decision-making by managers and has been described as the most important part of a business plan.