Non-functional requirements.
also: non-functional requirement · NFRs · NFR · quality attributesHow well the system does its job: latency, availability, throughput, durability, security and compliance targets.
the two-minute refresher
- Non-functional = how WELL the system does it: 99.99% uptime, <100 ms latency, 1M requests/s, encryption, GDPR.
- They drive the architecture, technology choices, infrastructure size and cost.
- Turn vague words into numbers: 'fast' becomes 'P99 under 200 ms'.
- Always clarify both kinds: functional says what to build, non-functional says how.