United States Dollar
In foreign exchange terminology, the United States or U.S. Dollar refers to the currency of the United States of America and is sometimes nicknamed the Greenback or Buck. The U.S. Dollar has the ISO 4217 code USD, and it is either the base currency or the counter-currency in the most commonly-traded currency pairs, although it generally trades as the base currency against most exotic currencies.
The United States Dollar acts as a reserve currency and is the main currency traded in the forex market. It commonly trades against the currencies of its major trading partners in currency pairs that include EUR/USD, USD/JPY, GBP/USD, USD/CHF, USD/CAD, AUD/USD and NZD/USD.