Modern economies become more and more open and the external sector of an economy becomes more and more important. This textbook aims at clarify ing how an open economy functions, in particular at explaining the determi nants of international fiows of commodities and financial assets. It also aims at examining the effects of these fiows on the domestic and international econ omy and the possible policy acti.ons at the national and international level. Particular attention will be paid to the problems of international economic at both the commercial and monetary level. integration Students will be able to read and interpret the balance of payments of a country, evaluating the various types of balance, to explain the behaviour of commercial fiows in the light of the theories studied, to analyze fiows of financial assets according to interest-rate differentials and other elements, to study the forces that determine exchange rates and cause currency crises, to understand the reasons behind international economic integration such as the European Union, to evaluate the effects of national and international policies.