An international exchange rate, also known as a foreign exchange (FX) rate, is the price of one country's currency in terms of another country's currency. Foreign exchange rates are relative and are expressed as the value of one currency compared to another. When selling products internationally, the exchange rate for the two trading countries' currencies is an important factor. Foreign exchange rates, in fact, are one of the most important determinants of a countries relative level of economic health, ranking just after interest rates and inflation. Exchange rates play a vital role in a country's level of trade, which is critical to most every free market economy in the world. Consequently, exchange rates are among the most watched, analyzed, and manipulated economic measures.