The generic definition of a requirement is “something essential to the existence or occurrence of something else.” In business, requirements refer to documented needs of what a particular product should be or how a service should perform. Requirements identify necessary attributes, capabilities, characteristics or qualities of a system in order for it to have value to a user. In short, requirements show what elements and functions are necessary for your project.
A list of requirements is often used in the vendor selection process to evaluate suppliers, clarify business needs and make them explicit. A requirements list plays an important part in an RFP.
Types of requirements
- Business requirements describe in business terms what must be delivered or accomplished to provide value.
- Product requirements describe the properties of a system or product.
- Process requirements describe activities performed by the supplier. For instance, they could specify specific methodologies to be followed, and constraints that the organization must obey.
- Functional requirements describe what a system must be able to do. They describe the functionality that the system is to execute, such as personalizing a newsletter or synchronizing with a CRM system. They are sometimes known as capabilities.
- Non-functional requirements specify something about the system itself, and how well it performs its functions. They are also known as “performance requirements” or “quality of service requirements.” Examples include how usable, available, reliable, supportable, testable and maintainable a system is.
- Constraint requirements impose limits upon the alternatives or project/process operations. No matter how the problem is solved, the constraint requirements must be met.