Functional Requirement
A precise, testable behavior that the product or service must carry out.
Key Points
- Defines what the solution does: actions, inputs, outputs, and rules.
- Different from non-functional requirements, which describe quality attributes like performance or security.
- Should be clear, measurable, traceable, and testable.
- Often captured as user stories, use cases, or acceptance criteria in agile backlogs.
Example
When a customer submits an order, the system validates the items, calculates tax, and sends a confirmation email within 1 minute.
PMP Example Question
Which of the following best represents a functional requirement for an e-commerce platform?
- The system must maintain 99.9% uptime during peak season.
- The application shall allow users to reset their password via a verification email.
- Stakeholder satisfaction should improve quarter over quarter.
- The project team will adopt Scrum with 2-week sprints.
Correct Answer: B - required product behavior
Explanation: Option B describes a specific behavior the product must perform, which is a functional requirement. The others are non-functional (A), a business goal (C), and a process choice (D).