International monetary systems are sets of internationally agreed rules, conventions and supporting institutions, that facilitate international trade, cross border investment and generally the reallocation of capital between nation states. They provide means of payment acceptable between buyers and sellers of different nationality, including deferred payment. To operate successfully, they need to inspire confidence, to provide sufficient liquidity for fluctuating levels of trade and to provide means by which global imbalances can be corrected. The systems can grow organically as the collective result of numerous individual agreements between international economic factors spread over several decades. Alternatively, they can arise from a single architectural vision as happened at Bretton Woods in 1944.