What is a requirements specification and why do we create one?

A systematically structured collection of requirements for a system or component — we write it down to create a shared, legally relevant, testable reference for everyone involved.

A requirements specification is a systematically represented collection of requirements, typically for a system or component, that satisfies given criteria.

Why we specify:

1. Requirements are the basis of system development
2. Requirements have legal relevance (contractual obligations)
3. Requirements documents are complex and need structure
4. Requirements must be accessible to all involved parties

Writing requirements down ensures shared understanding and provides a reference for development and testing.

What makes a good requirement (SMART-like criteria):

• Specific: Clear and unambiguous
• Measurable: Can be tested/verified
• Achievable: Technically feasible
• Relevant: Tied to business goals
• Traceable: Linked to source and tests

Bad: "The system should be fast" Good: "The search results page shall load within 2 seconds for 95% of requests under normal load (1000 concurrent users)"

Go deeper:

• Software requirements specification (Wikipedia) — what an SRS contains and how it is structured into purpose, description, and specific requirements.