A quality requirement defines how well a system must perform or which conditions it must satisfy.
It may address performance, availability, security, reliability, usability, maintainability, or portability. Therefore, it complements functional requirements, which describe system behaviour and capabilities.
Teams should express each quality requirement through measurable targets. For example, they may define a maximum response time, a required availability rate, or an access restriction.
Acceptance criteria provide specific conditions for verification. Moreover, tests, reviews, measurements, or certifications can supply objective evidence.
Some expectations affect one function. Others apply across the entire system. Consequently, teams should link them to all relevant requirements and reflect them in common completion criteria.
Vague terms such as “fast,” “secure,” or “user-friendly” require further refinement. Otherwise, stakeholders may interpret them differently.
Clear and measurable expectations support consistent implementation, objective testing, and reliable stakeholder acceptance.
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