The United States dollar (sign: $; code: USD) is the official currency of the United States of America. The U.S. dollar is normally abbreviated as the dollar sign, $, or as USD or US$ to distinguish it from other dollar-denominated currencies and from others that use the $ symbol.

It is divided into 100 cents. The U.S. dollar is the currency most used in international transactions and is one of the world's reserve currencies.

Several countries use it as their official currency, in many others it is the de facto currency, and it is also used as the sole currency in some British Overseas Territories.

Source: Wikipedia