Functional Requirements
Statements describing what a system must do to fulfill its intended purpose.
Functional requirements describe what a system should do—its expected behaviors and outputs in different situations.
Examples include how authentication should work, what data must be captured on certain forms, or how often background jobs should run. They are often documented in specifications, tickets, or design documents.
Clear functional requirements support better design, testing, and later compliance work, because they define what “correct behavior” means for a given system.