Regions are now everywhere across the globe and are increasingly fundamental to the functioning of all aspects of world affairs from trade to conflict management, and can even be said to now constitute world order. But to what extent are their origins, purposes, operating principles and wider consequences the same? An eminent and international collection of scholars examine the central but disputed concept of regions from a range of perspectives and assess leading contemporary examples. Rather than uncritically celebrating regions, the collection also offers some contrarian findings and wider lessons of interest across the study of International Relations and beyond.