There used to be a time when people were able to buy more than three articles or food ítems and pay with a ten dollar bill, and perhaps still have change to keep. Memories from the 70's and early 80's come around while checking my $10 starred bill. 

Many coin and paper money collecting houses advised in 2013 that star notes printed and circulating will be prized higher in the future. 

Star notes are printed in what are called "runs." For the current printing systems used by the BEP, the maximum run size for star notes is 3.2 million notes (100,000 32-note sheets).

Sometimes, this many notes are not needed, in which case less are printed. If a partial run is printed, the next run will start at the next closest multiple of 3.2 million.

Star notes get their rarity from the quantity printed and released into circulation. Generally, collectors consider runs of 640,000 notes or less to be rare. Many times, collectors refer to star notes by their run number. This is determined by the number range that the star note's serial number fits into. 

On Federal Reserve Notes, the star is where the block letter normally is (the last letter of the serial number).

On Legal Tender notes and Silver Certificates, the star is where the prefix normally is (the first letter of the serial number).

AC Coin$.