This book provides a comprehensive guide to foreign exchange from multiple perspectives, including professional practice, public policy, and academic research. It examines theories of exchange rate determination in light of how real-FX markets are structured and how FX transactions are actually conducted, and actual developments in foreign exchange rates. Furthermore, drawing on the author&s experience working at Japan&s Ministry of Finance, which is responsible for the country&s foreign exchange policy, the book offers detailed insights into exchange rate policy and the international monetary system. Overall, it bridges theory and practice, helping readers understand both the analytical frameworks used to interpret exchange rates developments and the institutional and market realities that shape outcomes.