USD is the abbreviation of United States Dollar and is the official currency of the United States. It is also known as the greenback or the buck and is the world’s primary reserve currency. This means that large quantity of US dollars are held by central banks and other financial institutions across the globe in reserves. Many commodities, like gold, silver and oil are also priced in USD, providing additional reason for other countries the hold US dollars.
USD is the most commonly converted currency on the global foreign exchange markets, accounting for approximately 88% of all global foreign exchange transactions. As such it is considered a “benchmark” currency. It is a fee floated currency with numerous other currencies pegged to the US dollar.