The most commonly used currency in the world is the U.S. Dollar (USD). It serves as the primary reserve currency for many countries, playing a critical role in global trade and finance. Due to its widespread acceptance, many businesses and individuals conduct transactions in USD, making it a standard medium for international trade. The U.S. Dollar is recognized for its stability and liquidity, which are key factors that contribute to its dominance. Many countries also peg their currencies to the dollar or hold it as a major part of their foreign exchange reserves. Thus, the USD remains a cornerstone of the global economic system.