This document provides an overview of theories of international trade, beginning with mercantilism and including absolute advantage, comparative advantage, factor proportions, product life cycles, new trade theory, and national competitive advantage. It discusses key aspects of each theory, such as how mercantilism aimed to accumulate wealth through trade surpluses while exploiting colonies, and how comparative advantage shows that trade benefits both parties even if one country is less efficient. Theories have evolved over time to better explain patterns of trade.