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Glossary · Requirements

Non-functional Requirements

Non-functional requirements (NFRs) specify the qualities a system must have: performance, scalability, security, accessibility, and reliability. They're easy to omit and expensive to retrofit, so strong specs state them explicitly with measurable targets (for example, 'p95 latency under 300 ms'). NFRs often determine whether a product is actually usable at scale.

Related terms
Product Requirements Document (PRD)
The document that defines what a product should do and why, for the team building it.
Definition of Done (DoD)
A shared checklist of everything that must be true before work is considered complete.
Acceptance Criteria
The conditions a user story must meet to be considered complete and correct.
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