7. Functional Requirements
in which we look at those requirements that cause the product to do something
The functional requirements specify what the product must do. They describe the actions the product must carry out to satisfy the fundamental reasons for its existence. For example, the functional requirement describes an action the product must take if it is to carry out the work for which it is intended. The intention is to understand the functional requirements and so convey to the developers what the product is required to do for its intended operator.