Non-functional requirements define how well the system performs.
Performance:
- Target load time? (under seconds?)
- Interaction latency? (under ms?)
- How many items to handle? (? ,?)
Accessibility:
- WCAG compliance level? (A, AA, AAA)
- Screen reader support needed?
Internationalization:
- How many languages?
- RTL support needed?
Offline:
- Work without network?
- Sync when back online?
Non-functional requirements shape architectural decisions. Ask about them explicitly.