Software Requirements Specification
A Software Requirements Specification (SRS) is a complete description of the behavior of the system to be developed. It is document explaining the requirements of a computer system from the user's point of view. It includes a set of use cases that describe all the interactions the users will have with the software. The requirements specification can also be used to assess if the software fulfills the requirements. [Wikipedia]
The requirements analysis and specification phase starts once the feasibility study phase is complete and the project is found to be financially sound and technically feasible. The goal of requirements analysis and specification phase is to clearly understand the customers requirements and to systemetically organize these requirements in a specification document. The Software Requirement Specification document is the final output of the requirements analysis and specification phase. [Source]