What Is The Rim Of A Coin?

By GovMint :

By definition, the rim of a coin refers to the raised edge that runs around the perimeter of the coin. The primary purpose of the rim is to protect the coin's design and inscriptions from wear and damage, as the rim is typically the highest point on a coin and the first area to show signs of wear through circulation. Additionally, the rim serves a security function by making it easier to detect counterfeit coins since elements like intricate reeding or other design techniques are often incorporated into the rim of coins for authentication purposes.

Sources Used:

https://www.usmint.gov/learn/kids/coins-life/parts-of-a-coin