A star note is a replacement note. USA banknotes are printed in sheets, stacked, and cut into bricks of 100 notes of consecutive numbers per bundle. When a sheet has a printing error, the BEP cannot release the bills and the sheet has to be replaced. In order to keep the bricks numbered 001 - 000 star notes are inserted as replacement notes so the number sequence isn't broken.

Star notes are printed in smaller quantities than "lettered" notes, and are usually more collectible.