What Is A Privy Mark?

By GovMint :

Historically, privy marks were commonly used to denote the location where a coin was minted, serving as a form of identification for the issuing mint. However, over the years, the function of privy marks has evolved beyond just indicating the mint of origin. While they still retain some ties to heritage and tradition, privy marks now more often than not signify special editions or commemorative themes rather than solely denoting minting locations. This shift has added a layer of complexity and intrigue to coin collecting.

Sources Used:

https://www.usmint.gov/news/inside-the-mint/privy-marks-on-coins