The basic unit of currency in the United States is the US dollar, symbolized by "$" and abbreviated as USD. The dollar has been in use since the late 18th century and is divided into 100 smaller units known as cents. The US dollar is one of the most widely used currencies in the world, serving as the primary reserve currency for international trade and finance. Its strength and stability are influenced by the US economy and monetary policy set by the Federal Reserve. The dollar is a critical component of global markets and transactions.