Digital currency is becoming increasingly important as apps, digital wallets, and access to debit and credit card readers evolve. However, physical currency still plays an important role in our lives.

Still, coins pass through our hands all the time with not so much as a second thought. One design you might not have even noticed to this point. But anyone who has sorted loose change or rolled coins for a bank has likely felt the difference between a smooth edge and a ridged one.

This isn’t a minting mistake or some small detail. Ridged coins date back centuries and are important to modern U.S. currency. Learn why some coins have ridges and others don’t, how coin design has evolved, and modern use of ridged coins.

Why Do Some Coins Have Ridges?

Olga Kaya/Getty Images

Coin ridges, more commonly referred to as “reeding,” are small grooves along the edge of coins.…