Functional Requirements define the desired behaviour or functionality of a system. They specify what the system should do.
Key Aspects:
1. User interactions
2. System responses
3. Data processing rules
4. Business logic
5. Feature specifications
Characteristics:
1. Clear and unambiguous
2. Testable
3. Traceable
4. Feasible
5. Consistent with other requirements Functional requirements guide development and testing processes. They form the basis for system design and implementation.