Q3: What is the difference between functional and non-functional requirements?
Functional requirements describe what the system does—for example, users can upload a photo or search products. Non-functional requirements describe how well it does it, such as latency, availability, durability, scalability, security, and cost. Non-functional requirements should be measurable where possible, such as p95 read latency below 200 ms or 99.95% monthly availability.
Key Takeaways
- Functional requirements define behavior; non-functional requirements define quality attributes.
- Turn vague goals into measurable targets.