Coins and banknotes are designed by institutions that think hard about fraud, durability and accessibility, so very little on them is accidental. Many features still on today's money were invented to solve problems that no longer exist in the same form.
These oddities trace those details back to the mints and central banks that use them, and explain both the original reason and why the feature was kept.
Money
The ridges, called reeding, began as an anti-theft feature. When coins were made of gold and silver, people clipped or filed metal from the edges and still spent the coins at full value. A ridged edge made any trimming obvious. Everyday coins no longer contain precious metal, but the ridges stayed, and they help people tell coins apart by touch.
New Shorts explain one everyday object in under a minute. Subscribe on YouTube so the next one finds you.
