The purpose of my book is to give an insight into economies of scale and economies of scope - two of the basic types of efficiency gains. There are no legal nor economic papers presenting the basic economics underlying these fundamental types of efficiency gains in a way that is accessible to lawyers and the general public. The main value of my book is to contribute to the legal conceptualization of economies of scale and economies of scope: it provides guidance on the nature and applications thereof for the purpose of legal doctrine and court work on antitrust cases.