What does the star next to the serial # on a one dollar bill do to its collectible value?

I was told to hold on to any one dollar bills that have an asterisk or star next to the end of the green serial number. I haven’t been able to figure out what it has to do with it’s collectible value or actual value. Any ideas?
Image by kentkb
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actaully it depends on how old the bill is. back in the day they used “SILVER CERTIFICATES” instead of “FEDERAL RESERVE NOTES”…. if it has an asterisk and is a “SILVER CERTIFICATE” hang on to it…. otherwise let it go
According to “How Stuff Works”:
“This star represents what is known as a replacement note. When a printing error occurs during a normal press run and renders a set of bills unusable, replacement notes are used instead. The replacement notes have a sequence of their own, using the star as their final “letter.”
In general, replacement notes aren’t worth more than regular bills. However, if you find a replacement note with a particularly interesting serial number — like 00000001 or 999999999 — or a large number of consecutively numbered replacement notes that you keep together as a lot, you may have a collector’s item on your hands.”