If you’re during the U.S., all real bills will likely have a watermark of the person whose portrait is about the bill. They’ll also have a safety thread embedded from the paper that glows below ultraviolet light-weight. Some trade dollar fakes have an used rim- they struck the coin 'disc' https://juliuslkoyj.acidblog.net/65367457/the-ultimate-guide-to-us-dollars-gov-copyright