The vocabulary and discourse of water resource management have expanded vastly in recent years to include an array of new concepts and terminology, such as water security, water productivity, virtual water and water governance. While the new conceptual lenses may generate insights that improve responses to the world’s water challenges, their practical use is often encumbered by ambiguity and confusion. This book applies critical scrutiny to a prominent set of new but widely used terms, in order to clarify their meanings and improve the basis on which we identify and tackle the world’s water challenges. More specifically, the book takes stock of what several of the more prominent new terms mean, reviews variation in interpretation, explores how they are measured, and discusses their respective added value. It makes many implicit differences between terms explicit and aids understanding and use of these terms by both students and professionals. At the same time, it does not ignore the legitimately contested nature of some concepts. Further, the book enables greater precision on the interpretational options for the various terms, and for the value that they add to water policy and its implementation.