How many types of currency in usd?

The United States has several types of currency, primarily the paper bills and coins issued by the U.S. Department of the Treasury and the Federal Reserve. The main denominations of paper currency are $1, $5, $10, $20, $50, and $100 bills. Additionally, there are coins in denominations of 1 cent (penny), 5 cents (nickel), 10 cents (dime), 25 cents (quarter), and dollar coins. In total, there are six main types of paper currency and several coin denominations.