Open-economy macroeconomics deals with the mechanisms of adjustment in balance-of-payments disequilibria (deficits and surpluses). More importantly, it analyses the relationship between the internal and external sectors of the economy of a nation, and how they are interrelated or interdependent with the rest of the world economy under different international monetary systems.

International trade theory and the policies are the microeconomic aspects of international economics because they deal with individual nations treated as single units and with the relative price of individual commodities. on the other hand since the balance of payments deals with total receipts and payments, as well as with adjustment and other economic policies that affect the level of national income and the general price level of the nation as a whole, they represent the macroeconomic aspects of international economics. These are often referred to as open-economy macro-economics or international finance.

International economic relations differ from interregional economic relations (i.e., the economic relations among different parts of the same nation), thus requiring somewhat different tools of analysis and justifying international economics as a distinct branch of economics. I.e. nations usually impose restrictions on the flow of goods, services, and factors across there borders, but not internally .in addition, international flows are to some extent hampered by difference in language, customs, and laws. Furthermore, international flows of goods, services, and resources give rise to payments and receipts in foreign currencies which change in value over time.

International economics has enjoyed a long, continuous, and rich development over the past two centuries, with contributions from some of the world’s most distinguished economics, from Adam Smith to David Ricardo, John Smart Mill, Alfred Marshall, John Maynard Keynes, and Paul Samuelsson.