A Product Scope Document is a comprehensive guide that outlines the key elements of a project. 

It serves as a central reference to capture the objectives, deliverables, requirements, and constraints of a product or project. 

This document ensures that all stakeholders have a clear and consistent understanding of what is being developed, why it is needed, and how it will be executed. 

By providing this clarity, a Product Scope Document helps align expectations, prevent scope creep, and facilitate efficient project management.