Have a look at some change in your pocket and you’ll see that mostly coins have ribbed edges as if they are scarred. Such textured surface can be observed in almost every coin of the world no matter where it came from. Such coins appeared several centuries ago. So why are all of them ribbed?
The story says that once upon a time coins were evaluated by the amount of precious metal contained in each. Look at these adorable ancient Greek ones:
These are made of electrum which is a naturally occuring alloy of gold and silver. Not only they are of irregular shape, the edges are smooth with no marks or scratches on them. So, for example, $\$$10 coin contained the precise amount of gold that was equal to those $10. Frauds used to cut the edges of coins to make new ones for their own profit. Preventive measures had to be taken. It was quite a serious issue since not every man could carry a pair of scales to check whether the coin is cut or not.
To tackle with knaves’ tricks, it was decided to gouge small lines on the coin edges. Due to this they became distinguishable enough. This extraordinary method was suggested by the very famous at that time and nowadays, physicist and Warden and Master of the British Royal Mint, Isaac Newton. The idea seemed to be simple and brilliant at the same time. Eventually, all coins were marked and swindle dropped to zero. And no wonder – when one came across coin with smooth edges, they at once understood it had been cut.
Noble metals, such as gold and silver, are no longer used in coin production. However, lines on edges still exist. Germany introduced notched coins only in 1648 in Clausthal, which is now famous for its resort Clausthal-Zellerfeld. In 16th century, a special mechanism to lay inscriptions on coins was invented in France. It helped to improve this unpretentious thief protecting technology and stop the crime of clipping. The first lettering appeared in 1577 on French golden ecu.
The necessity of this method in present day world goes down as paper bills are more valued. Lots of engineering techniques like security printing were invented to protect banknotes against counterfeiting. Moreover, due to digitalisation of financial activities, soon paper money become completely obsolete freeing the way for something like bitcoins, or cryptocurrency, where encryption substitutes ribbed edges and stuff. But we can’t deny this time-honored tradition, which, besides, helps blind people to differentiate coins. You can observe the long process of coin manufacturing on the US Mint website. It states that 10 cent coin has 118 lines, 119 lines go to 25 cent, and 150 – to 50 cent. 1 and 5 cent coins don’t have such marks as they have never been made of precious metals.