In Understanding International Trade, Reto Foellmi and Stefan Legge provide a clear, structured, and profound introduction to the theory of international trade. Designed for students and practitioners with an interest in global economics, the book explains why nations trade, how trade affects welfare and income distribution, and what determines the patterns and volume of global trade flows. Starting with the earliest trade models, such as Ricardo's theory of comparative advantage, the book walks through a range of foundational and advanced models, seeking a deep understanding while avoiding technical overload. It includes the Heckscher-Ohlin framework, specific-factors models, the Dornbusch-Fischer-Samuelson and the Eaton-Kortum model. It then transitions to modern trade theory, covering increasing returns to scale, monopolistic competition, and firm-level heterogeneity as in the Krugman and Melitz models. Each model is presented with a clear setup, graphical illustrations, and economic intuition, allowing readers to understand the underlying mechanisms as well as policy implications. The book emphasizes both the theoretical and empirical relevance of trade models. It explains how trade costs, productivity differences, and endowment structures influence trade flows, and introduces tools like the gravity equation for analyzing real-world data. While it focuses on real trade in goods, it also touches on factor mobility and the role of institutions in shaping trade outcomes. A comprehensive yet approachable guide with exercises at the end of each chapter, this book offers a better understanding of the logic, structure, and real-world relevance of international trade theory.