This book focuses on various topics related to engineering and management of requirements, in particular elicitation, negotiation, prioritisation, and documentation (whether with natural languages or with graphical models). The book provides methods and techniques that help to characterise, in a systematic manner, the requirements of the intended engineering system. It was written with the goal of being adopted as the main text for courses on requirements engineering, or as a strong reference to the topics of requirements in courses with a broader scope. It can also be used in vocational courses, for professionals interested in the software and information systems domain. Readers who have finished this book will be able to:- establish and plan a requirements engineering process within the development ofcomplex engineering systems;- define and identify the types of relevant requirements in engineering projects;- choose and apply the most appropriate techniques to elicit the requirements of agiven system;- conduct and manage negotiation and prioritisation processes for the requirementsof a given engineering system;- document the requirements of the system under development, either in naturallanguage or with graphical and formal models. Each chapter includes a set of exercises.