Functional Requirements
Functional requirements specify what a system must do — the specific behaviours, features, and capabilities required to meet business needs and stakeholder expectations.
Full Definition
Functional requirements define the system's behaviour in response to specific inputs or in specific situations. They answer the question 'what should the system do?' — as opposed to non-functional requirements, which answer 'how well should it do it?' Every functional requirement should be testable, unambiguous, traceable to a business need, and accompanied by clear acceptance criteria that define what 'done' looks like.
Characteristics
- Specific: describes a single, discrete behaviour
- Measurable: has testable acceptance criteria
- Traceable: links back to a business requirement or user story
- Unambiguous: only one interpretation possible
- Complete: all inputs, outputs, and exceptions documented
Frequently Asked Questions
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