Walras’ Law is a principle in general equilibrium theory asserting that when considering any particular market, if all other markets in an economy are in equilibrium, then that specific market must also be in equilibrium. Walras’ Law hinges on the mathematical notion that excess market demands (or, inversely, excess market supplies) must sum to zero.

A reserve currency (or anchor currency) is a currency which is held in significant quantities by many governments and institutions as part of their foreign exchange reserves. It also tends to be the international pricing currency for products traded on a global market, such as oil, gold, etc.

An open economy is an economy in which people, including businesses, can trade in goods and services with other people and businesses in the international community at large. This contrasts with a closed economy in which international trade cannot take place.