Reach into your pocket right now and grab a handful of change. Go ahead. Feel around. Some of those coins have smooth edges. Others have tiny ridges running all the way around the rim. Most of us have touched coins a thousand times without ever stopping to wonder why.

Turns out, there’s a pretty great story behind it.

Those ridges have a name. Coin experts call them “reeding,” and they’ve been part of currency design for centuries. Not an accident. Not a decoration. Reeding was actually invented to stop thieves.

Here’s the problem early mints were trying to solve. When coins were made of gold and silver, criminals figured out a nasty little trick called “shaving.” They’d scrape tiny amounts of metal off the edges of coins, pocket the shavings, and then spend the coin as if nothing had changed. Do that enough times with enough coins, and you’ve collected real precious metal essentially for free. The coin still looked like a coin. Nobody was the wiser.

Reeding fixed that instantly. The moment you file down even a sliver of a ridged edge, it shows. The grooves disappear where you’ve shaved. Anyone who glances at the edge knows something’s wrong. No ridges, no good.

So why don’t pennies and nickels have ridges? Simple economics, honestly. Lower-value coins have always been made from cheaper metals, so shaving them wasn’t worth the effort for thieves. The cost of the crime outweighed what you’d gain. Quarters and dimes, being worth more, kept their reeding. That logic carried forward even as U.S. coinage shifted away from precious metals entirely.

The thing is, modern quarters and dimes aren’t silver anymore. They’re mostly copper and nickel sandwiched together. Nobody’s shaving them for profit. But the ridges stayed.

Why? Because they still do real work.

Think about sorting coins in the dark, or digging through your center console without looking at the road. You can tell a dime from a penny just by running your thumb along the edge. Smooth means penny or nickel. Ridged means dime or quarter. That’s useful for everyone, but especially for people with visual impairments who rely on touch to identify money every single day. The American Foundation for the Blind has long pointed to tactile coin features as an important accessibility tool that gets quietly overlooked in conversations about inclusive design.

Cashiers moving fast, collectors sorting through jars, vending machines reading coins mechanically, parents teaching their kids about money at the kitchen table. All of them benefit from that simple ridged edge.

The process of actually adding reeding is pretty cool. At the U.S. Mint, large metal coils are cut into flat discs called blanks. Those blanks get softened with heat, cleaned, and run through an “upsetting mill” that raises a rim around the edge. Once a blank becomes a planchet, it goes into a press that stamps the front and back designs at the same time a collar shapes the ridged edge. The whole thing happens in one strike.

And the details are surprisingly precise. Dimes get exactly 118 reeds. Quarters get 119. Not approximately. Exactly.

Here’s what I love about this as a mom who’s sat at the table with my kids counting up birthday money. Coins are one of the first physical objects kids really handle and study up close. There’s something powerful about telling them that this tiny detail on the edge of a quarter isn’t random, that someone designed it on purpose, that it solved a real problem, and that it’s still solving problems today for people who can’t see. That’s history and engineering and empathy all on a ten-cent coin.

We’re seeing more digital payments everywhere, sure. But physical coins aren’t going anywhere fast, and honestly, I think that’s fine. There’s something grounding about actual money in your hand. Something real.

According to Family Handyman, reeding remains one of those overlooked design details that’s done exactly what it was meant to do for a very long time.

So next time you’re rolling coins for the bank or fishing a quarter out of the car seat, take a second. Run your thumb around that edge. Those little ridges outlasted gold coins, silver coins, and about three hundred years of people trying to cheat the system. Still going strong.