Explain the difference between a business requirement, a functional requirement, and a user story, using one example that runs through all three.

1. A business requirement states the outcome the organisation needs: “Reduce the average time from opportunity close to invoice issue from nine days to two.” It is solution-agnostic and tied to value.
2. A functional requirement states what the system must do to support that outcome: “When an Opportunity reaches Closed Won, the system must generate an invoice record populated from the Opportunity's line items.”
3. A user story expresses the same capability from a user's perspective, sized for a sprint: “As a finance administrator, I want an invoice created automatically when an Opportunity is Closed Won, so that I no longer re-key line items manually.”
4. The story then carries acceptance criteria in Given/When/Then form that make it testable.
5. The practical value of the chain is traceability: if someone challenges the story in sprint three, I can point upward to the functional requirement and the business objective that justify it.