Mastering the Requirements Process

The non-functional requirements describe the qualities that your product must have or, to put that another way, how well it does the things it does. Such requirements make the product attractive, or usable, or fast, or reliable, or safe. You use non-functional requirements to specify response times, or accuracy limits on calculations. You write non-functional requirements when you need your product to have a particular appearance, or be used by people in particular circumstances, or adhere to laws applicable to your kind of business. These properties are not required because they are the functional activities of the product—activities such as computations, data manipulations, and so on—but rather are included because the client expects ...