Updated with new developments, ideas and thinking, as well as new tool descriptions, the fourth edition of this popular book is driven by practical experience from industry. It provides invaluable information on how to write and structure requirements, whilst explaining the importance of Systems Engineering and the creation of effective solutions to problems. This edition contains an expanded discussion of “design agnosticism� as an important principle in Requirements Engineering, and new insights regarding the validation and verification process in the context of the Systems Engineering “V� model. Further new elements include a discussion of SysML in the chapter on modelling techniques, and the use of SysML diagrams to present the generic process. Readers will also discover the latest thinking on requirements flow-down and rich traceability and an update to the chapter on tools to present DOORS Next Generation. Requirements Engineering is written by practitioners for practitioners and students who want to develop their knowledge of the subject area.