Likewise, security features have improved over time as currency is redesigned, so old bills may be more difficult to evaluate. However, some security features vary by denomination. Note: Most of the examples we use in our guide are of a $20 bill because it is the most counterfeited denomination of currency in the US. Counterfeiters can sometimes duplicate one or two of these unique characteristics but rarely all of them. The Bureau of Engraving and Printing designs and produces Federal Reserve Notes to include a number of security features.
8 Security Features to Detect Counterfeit Money
