One dollar is a unit of currency used primarily in the United States and several other countries. It is represented by the symbol $ and is divided into 100 smaller units called cents. The U.S. dollar is issued by the $Federal Reserve and is one of the most widely used currencies in the world. The dollar comes in both paper and coin forms. Paper bills are available in denominations of $1, $5, $10, $20, $50, and $100. Coins include the $1 coin, as well as smaller denominations like the $0.25 quarter and the $0.10 dime.