Functional requirements define what the system does.
Questions to ask:
- What are the core user flows?
- What actions can users take?
- What data needs to be displayed?
- What interactions are required?
Example for autocomplete:
- Show suggestions as user types
- Highlight matching text
- Select suggestion via click or keyboard
- Submit on Enter
Interview tip: List - core requirements. Ask: "Should I prioritize any of these?" This shows you understand scoping.