Functional requirements define what a system should do, describing features, capabilities, and behavior.

Explanation:

• Includes inputs, outputs, workflows, data processing.
• Expressed in Software Requirement Specification (SRS) documents.
• Must be clear, testable, and traceable.

Example:

• For an e-commerce website:
  • Users should be able to add products to a cart.
  • Customers must complete payment through PayPal or credit card.
  • Admins should generate monthly sales reports.