Many years ago, coins were made out of precious metals such as gold and silver. This tempted some people to file flakes of the valuable metals from the edges of the coins and then accumulate the shavings. Some coins, in particular the British sterling-silver coins, were often shaved by opportunist money-handlers to half their minted weight. Merchants were obliged to weigh coins in order to ensure that they were fit and proper, and this of course had an adverse impact on their rate of business. Each incumbent monarch of England during the Tudor Period was forced to recall coins periodically and have them reminted.

To combat this problem, ridges were carved into the edges of most of the valuable coins. If the ridges remained unaltered, this showed that none of the precious metal had been shaved off and the coin was still good legal tender. Also, the ridges - collectively known as reeding or milling, while the shapes of the ridges were known as crests and troughs - made counterfeiting more difficult. Only the valuable coins were reeded unnecessary, as an opportunistic coin-shaver would need to flake off a huge amount of such metal in order to make his efforts worthwhile.

Today, no coins are made from precious metals, but the tradition of reeding has continued on coins of higher value. In modern times, reeding also helps people who are visually impaired to tell the difference between the various coins, as each is reeded in a different way, while the lower-denomination coins aren't reeded at all. It's therefore possible to distinguish between coins simply by feeling the edge.