The types of requirements defined for a computer based system are as highlighted below:
Generally, system requirements are intended to communicate the functions that the system should provide. And every computer based systems consists of many requirements. They are;
1. User requirements
2. System requirements
3. Functional requirements
4. Non-functional requirements
Description for requirements
User requirements: These requirements are the statements in a natural language plus diagrams of the services the system provides and its operational constraints.
System requirements: A structured document setting out detailed descriptions of the system’s functions, services and operational constraints. Defines what should be implemented. It may be part of a contract between client and contractor.
Functional requirements: These are the statements of services that the system should provide, how the system should react to particular inputs and how the system should behave in particular situations.
Non-functional requirements: Constraints on the services or functions offered by the system such as timing constraints, constraints on the development process, standards, etc.
These requirements are usually applied to the system as a whole rather than individual features or services.