An SRS is a document that helps establish the foundation for an agreement between parties such as clients, contractors and suppliers. It outlines what the overall expectations are and what the software is going to do – and not do. As this document requires a thorough evaluation of requirements before the design phase, it helps to drastically reduce the need to redesign later.
Everyone involved in the development process relies on the SRS to be the focal point for planning, design, coding and testing. The document should be a realistic basis for estimating product costs, risks and schedules – which helps to prevent failures or delays.