Coin edge
Coin edges are the parts of a coin's surface between the faces; they may be plain or patterned, or a combination of both. They can also include lettering.
Reeded edges are often referred to as "ridged" or "grooved", or "milled". Some coins, such as Quarter (United [States coin)|United States quarters] and dimes, have reeded edges. Reeding of edges was introduced to prevent coin clipping and counterfeiting.
The main techniques of coin edging are edge mills of various types, which put a pattern on a smooth edge, after a coin and coin mills with edge rings, which pattern the edge at the time when the coin is being milled.