The design requirements specify the functions that the design must perform and the objectives that the design must meet.
There are two types of requirements: functional requirements and nonfunctional requirements. Functional requirements specify the objectives or functions that a design must meet. Nonfunctional requirements define how the design accomplishes the functional requirements.
Typical functional requirements include the following:
Business goals
Business rules
Legal, regulatory, and compliance requirements
Application system requirements
Technical requirements
Administrative functions
Typical nonfunctional requirements include the following:
Performance
Security
Capacity
Availability
Manageability
Recoverability
When identifying and defining the requirements, separate the functional requirements from the nonfunctional requirements. Nonfunctional requirements are design constraints and will be documented separately.