Requirement is a condition or capability possessed by the software or system component in order to solve a real-world problem. Requirement describes how a system should act, appear or perform. For this when user request for software, they provide an approximation of what new system should be capable of doing. Requirements differs from one user to another and one business process to another.
BABOK, which is recognized set of business analysis industry standards, offers the following classification of requirements.
Business Requirements:
These includes high level statement of goals, objectives and needs. Business requirement doesn’t include any specific features. They just state the problem and the business objective to be achieved.
User requirement/stakeholder requirement:
It describes the need of the stakeholders that must meet the need of business requirements. The need of discrete stakeholder groups top level managers, nonmanagement staff, customers are they specified they want from a particular solution. They bridge the gap between the business requirement and solution requirement.
Solution requirement:
Solution requirement that describes the specific characteristic that product must have meet the need of stakeholders and its business itself. They provide an appropriate level of detail to the development and the implantation of the solution. Solution requirement can be divided into two categories:
Functional requirements: Functional requirements are the product features or the functions that developers must implement to enable user to accomplish their task. Generally functional requirement talks about the behavior of the system in a particular specific condition.
Nonfunctional requirements: Nonfunctional requirement is a requirement that specifies criteria that can be used to judge the operation of the system, rather than the specific behaviors. Nonfunctional requirement defines system attributes such as security, reliability, performance, maintainability, scalability.
Transition requirement: Transition requirement is a temporary requirement to facilitate the requirement from current state to desired state. They are only required for only short period of the time while transition takes place. Transition requirements address the topics such as data conversion, training and business continuity.