Requirements : ?

What is requirement? According to Wikipedia, a requirement is a singular documented physical and functional need that a particular product or service must be or perform. In other words, requirement is a statement about an intended product that specifies what it should do or how it should perform. It should be as specific, unambiguous and as clear as possible and we must know how to tell when they have been fulfilled. It is most commonly used in a formal sense in systems engineering, software engineering, or enterprise engineering. There are types of requirements; Functional Requirements and Non-Functional Requirements. Functional requirement captures the intended behavior of the system. This behavior may be expressed as services, tasks or function the system is required to perform or in a simpler way, it is what the system should do. Non-Functional requirement includes constraints and qualities. Qualities are properties or characteristics of the system that its stakeholders care about and hence will affect their degree of satisfaction with the system while a constraint is a restriction on the degree of freedom we have in providing a solution.