A requirements document is a formal document that outlines the specific needs and expectations for a project or product. It serves as a guide for stakeholders, including developers, designers, and clients, ensuring everyone has a clear understanding of what is to be delivered. This document typically includes functional and non-functional requirements, use cases, and any constraints that may affect the project. The purpose of a requirements document is to minimize misunderstandings and provide a reference point throughout the project lifecycle. By clearly defining the objectives and criteria for success, it helps teams stay aligned and focused on delivering a product that meets the needs of its users and stakeholders.