United States dollar . The United States dollar ( sign : $ ; code : USD ; also abbreviated US$ and referred to as the dollar , U.S. dollar , or American dollar ) is the official currency of the United States and its insular territories per the United States Constitution . The U.S. dollar is commodity money of silver as enacted by the Coinage Act of 1792 which determined the dollar to be 371 4/16 grain ( 24.1 g ) pure or 416 grain ( 27.0 g ) standard silver . Since the currency is the most used in international transactions , it is the world 's primary reserve currency . Several countries use it as their official currency , and in many others it is the de facto currency . Besides the United States , it is also used as the sole currency in two British Overseas Territories in the Caribbean : the British Virgin Islands and Turks and Caicos Islands .
The United States dollar is not a form of currency.