Software Requirements Specification SRS

Question. What is a Software Requirements Specification? What Kind of Information Should an SRS Include?
Answer.
A Software Requirements Specification (SRS) is a complete description of the behavior of the system to be developed. It includes a set of use cases that describe all the interactions the users will have with the software. Use cases are also known as functional requirements. In addition to use cases, the SRS also contains nonfunctional (or supplementary) requirements. Non-functional requirements are requirements which impose constraints on the design or implementation (such as performance engineering requirements, quality standards, or design constraints).

A sample of a basic SRS outline:
1. Introduction
1.1 Purpose
1.2 Scope
1.3 Definitions, acronyms, and abbreviations
1.4 References
1.5 Overview

2. Overall Description
2.1 Product perspective
2.2 Product functions
2.3 User classes and characteristics
2.4 Operating environment
2.5 User environment
2.6 Design/implementation constraints
2.7 Assumptions and dependencies

3. External Interface Requirements
3.1 User interfaces
3.2 Hardware interfaces
3.3 Software interfaces
3.4 Communication protocols and interfaces

4. System Features
4.1 System feature A
4.1.1 Description and priority
4.1.2 Action/result
4.1.3 Functional requirements
4.2 System feature B

5. Other Nonfunctional Requirements
5.1 Performance requirements
5.2 Safety requirements
5.3 Security requirements
5.4 Software quality attributes
5.5 Project documentation
5.6 User documentation

6. Other Requirements
Table of Contents and Index
Appendix A: Terminology/Glossary/Definitions list
Appendix B: To be determined

References:

http://www.techwr-l.com/techwhirl/magazine/writing/softwarerequirementspecs.html

http://en.wikipedia.org/wiki/Software_Requirements_Specification

http://www.microtoolsinc.com/Howsrs.php