Requirements management is the process of identifying the individual requirements and needs of stakeholders and developing these into detailed, agreed-upon requirements that are documented and specified in such a way that they can serve as a foundation for all subsequent system development activities. In this textbook, Klaus Pohl provides a comprehensive and well-structured introduction to the fundamentals, principles, and techniques of requirements management. He presents proven techniques for eliciting, negotiating, documenting, validating, and managing requirements for software-intensive systems. The various aspects of the process and the techniques are illustrated with numerous examples based on his extensive teaching experience and work in the industry. His presentation is aimed at professionals, students, and instructors in systems and software engineering or business application development.