A Software Requirements Specification (SRS) is a detailed document that outlines the expected behavior and features of a software system. It serves as a guide for developers, stakeholders, and project managers, ensuring everyone has a clear understanding of what the software should achieve. The SRS typically includes functional requirements, non-functional requirements, and constraints. The SRS is crucial for successful software development, as it helps prevent misunderstandings and scope creep. By providing a clear framework, it facilitates communication among team members and serves as a reference point throughout the software development lifecycle, from design to testing and maintenance.