A limited edition print is limited, forever, to the total number detailed in the original edition. If your print is number 5 of 15 then that means, the 5th numbered print in a total edition of 15.
The photographer may hold additional prints:
Artists Proofs (APs) numbering up to a maximum of 10% of the edition.
Printer's Proofs (PPs) which are usually kept by the printer.
Hors Commerce prints (HCs) which are used by the publisher for promotional purposes.
Artist's proofs are not included in the count of a limited edition, and they belong to the artist. The artist is not supposed to sell these AP's.
Sometimes limited editions are published in distinctly different sizes.
An artist's proof is used to describe an impression of the finished work that is identical to the numbered copies. For the printer and artist to check the printing quality of the finished image, the printer is allowed to keep a printer's proof.
PROOF OF AUTHENTICITY
All limited-edition prints come with a registered proof of authenticity. The work is registered in an online database and proofed with a numbered hologram on the back of the print. The same unique numbered hologram is also added to the signed proof of authenticity.