Non-functional requirements (NFRs) in software engineering are essential for defining the qualities and behaviors of a system that are not directly tied to specific functions. This book provides a comprehensive framework for understanding, acquiring, and managing NFRs. It covers the nature of NFRs, their categorization, and their relationship with functional requirements. The book discusses various types of NFRs, including accuracy, security, and performance requirements, and presents methods for decomposing, operationalizing, and evaluating them. It also explores the interdependencies among NFRs and how they influence design decisions. The text includes case studies and applications, such as a credit card system and an administrative system, to illustrate the practical use of the NFR framework. The book emphasizes the importance of recording design rationale, selecting alternatives, and evaluating the impact of decisions on the system. It also addresses the challenges of managing NFRs in complex systems, such as information systems, and provides strategies for organizing performance methods and correlations. The authors present a structured approach to handling NFRs, including the use of softgoal interdependency graphs and argumentation methods. The book is intended for software engineers, researchers, and practitioners interested in improving the quality and reliability of software systems through effective management of non-functional requirements.Non-functional requirements (NFRs) in software engineering are essential for defining the qualities and behaviors of a system that are not directly tied to specific functions. This book provides a comprehensive framework for understanding, acquiring, and managing NFRs. It covers the nature of NFRs, their categorization, and their relationship with functional requirements. The book discusses various types of NFRs, including accuracy, security, and performance requirements, and presents methods for decomposing, operationalizing, and evaluating them. It also explores the interdependencies among NFRs and how they influence design decisions. The text includes case studies and applications, such as a credit card system and an administrative system, to illustrate the practical use of the NFR framework. The book emphasizes the importance of recording design rationale, selecting alternatives, and evaluating the impact of decisions on the system. It also addresses the challenges of managing NFRs in complex systems, such as information systems, and provides strategies for organizing performance methods and correlations. The authors present a structured approach to handling NFRs, including the use of softgoal interdependency graphs and argumentation methods. The book is intended for software engineers, researchers, and practitioners interested in improving the quality and reliability of software systems through effective management of non-functional requirements.