This introduction presents an overview of the key concepts discussed in the subsequent chapters of this book. The book explores the strategies used by planners to reinforce their position in front of other well-protected interests. It aims to discover how planners can use different policy instruments, coming from either public or private law, to support the implementation of land use plans. The book also aims to bring together examples from different national contexts in order to raise the awareness on how specific instruments are used by planners in other countries. It highlights how planning practices and scarcity interact with one another. In a context where greenfield development always becomes more problematic because of the high resource consumption that is bound with it, building land becomes scarcer. The book claims that this scarcity is mostly constructed by the complex entanglement of property rights that characterize the already built environment.