Requirements

Requirements are precise statements that describe the capabilities, conditions, and constraints a system or project must meet. They translate stakeholder needs into a basis for design, development, testing, and validation. Good requirements define what a product should do (functional requirements) as well as how well it should perform, behave, or operate under certain conditions (non-functional requirements).

Functional requirements specify tasks, data handling, interactions, and outputs. Non-functional requirements cover performance, reliability, security, usability, maintainability, portability, compliance, and constraints such as deadlines or budgets.

Requirements engineering is the discipline of eliciting, analyzing, documenting, validating, and managing requirements throughout the life cycle. Elicitation involves gathering information from stakeholders, users, and experts using interviews, workshops, use cases, user stories, and observations. Documentation can take the form of a software requirements specification, product backlog, or other artifacts. Traceability links requirements to design elements, implementation, and tests to ensure coverage.

Validation and verification ensure requirements are correct, complete, unambiguous, feasible, verifiable, and testable. Acceptance criteria define how a requirement is deemed satisfied. Standards such as IEEE 830 and ISO/IEC/IEEE 29148 provide guidance on structure and quality. In agile development, user stories with explicit acceptance criteria and incremental refinement are common.

Common challenges include ambiguity, incompleteness, conflicting requirements, and scope creep. Proper management, stakeholder involvement, change control, and ongoing verification help maintain alignment with business objectives and user needs.