Requirements management is the systematic process of eliciting, documenting, analyzing, tracking, and validating the needs and expectations of stakeholders throughout a project's lifecycle. Rooted in business analysis and systems engineering, it serves as the critical bridge between stakeholder vision and successful delivery, ensuring that what gets built aligns with what's actually needed. A well-managed requirements process prevents costly rework, scope creep, and project failure—studies consistently show that requirements defects discovered late in development cost exponentially more to fix than those caught early. The discipline balances competing concerns: capturing enough detail to be actionable while remaining flexible enough to accommodate change, all while maintaining traceability from business goals through implementation to acceptance testing.