In this introductory chapter of the book, the author defines the case study, explains the function of case studies, and explains the concept of the book. It gives an overview of the case universe, highlights some of the similarities and differences of different case studies and describes the use of geometric shapes to conceptualise the case writer’s toolkit. The author focuses on three genres of case studies in this book—the teaching case, research case and knowledge-capture case. There is a description of how each of these genres evolved, including some of their developments in Asia. The author gives a good background of how case studies came about. With this knowledge, case writers can better decide how they want to use the case studies that they write.