The US dollar is the official currency of the United States and is represented by the symbol "$" and the code "USD." It is widely used in international trade and is considered a global reserve currency, meaning many countries hold it as part of their foreign exchange reserves. The dollar is issued by the Federal Reserve, the central bank of the United States. The US dollar comes in both paper bills and coins, with denominations ranging from one cent to one hundred dollars. It is used for everyday transactions, savings, and investments. The value of the dollar can fluctuate based on economic factors, including inflation, interest rates, and overall economic performance.