The United States is a highly developed mixed economy. It is the world's largest economy by nominal GDP and the second largest by purchasing power parity. As of 2025, it has the world's 7th highest nominal GDP per capita and the 9th highest GDP per capita in BPP. According to the World Bank, the US accounted for 14.8% of the global aggregate GDP in 2024 in purchasing power parity terms. The US dollar is the currency of the record most used in international transactions and is the world's reserve currency, backed by a large U.S. Treasury market. Its role is the reference standard for the petrodollar system and is linked to the Eurodollar. Several countries use it as their official currency and in others it is a de facto currency. Since the end of World War II, the economy has achieved relatively steady growth, low unemployment and inflation, and rapid advances in technology.