This document discusses various trade theories: - Mercantilism focused on acquiring gold and saw trade as zero-sum, while absolute advantage explained trade through differences in productivity. - Comparative advantage built on this to show that all countries can benefit by specializing in what they're relatively best at producing. - Factor endowment theory argues countries export goods intensive in local factors they have in abundance. - More modern theories include product life cycle, new trade based on economies of scale, and national competitive advantage focusing on a nation's determinants. The aim of trade theories is to explain trade patterns and their impacts, and guide public policy to increase national well-being.