requirementstypes

Requirementstypes is a concept in requirements engineering that refers to the categories used to classify requirements for a project. The classification helps teams organize stakeholder needs, guide elicitation, and support verification and validation.

The two broad categories are functional requirements and non-functional requirements. Functional requirements describe what the system should do, such as actions, data processing, or interactions with users or other systems. Non-functional requirements define how the system should be, including performance, reliability, security, maintainability, usability, and compliance. Non-functional requirements are often subdivided into quality attributes, constraints, and standards the system must meet.

Other common classifications include stakeholder requirements, system requirements, and software requirements. Stakeholder requirements capture high-level objectives and expectations from business owners or users. System requirements translate these into capabilities within the broader system boundary, while software requirements specify the behavior and performance of the software component. Requirements traceability links each requirement to its origin and to corresponding design elements and test cases.

Standards and practices provide guidance for categorization and documentation. IEEE 29148 (Requirements Engineering) and related ISO/IEC/IEEE guidance offer structured approaches to capturing, organizing, and maintaining requirements. In practice, teams use taxonomies to improve clarity, change management, and traceability. Prioritization methods such as MoSCoW are often used in conjunction with requirement types to decide which items to implement first.

Best practices emphasize measurable acceptance criteria, unambiguous and verifiable statements, a single source of truth, and robust traceability from business goals to implementation. See also requirements engineering, requirements specification, traceability matrices, and quality attributes.