True story: I walked into a co-working space where I've been putting in time lately, and locked eyes with a newcomer

I knew him from somewhere. I couldn't remember where.

Me being me, I introduced myself. We were cordial, played the name game for a minute. 

Then I asked him: You weren't ever in the U.S. Army, were you?

Sure enough, he had been. He rattled off all of the positions he'd held, and we realized we overlapped for a few months many years ago at one installation, when I was called up as a reservist.  

Honestly, I could barely keep up as he described it all. For anyone else listening who hadn't been in, the abbreviations and shorthand would have sounded like alphabet soup.

The military, like so many other callings in life, has its own language. Its own codes.

This article is about another one of those occupational codes -- something that I suspect many people who read this will know very little about, but means something to millions of our fellow Americans.

The issue comes up with the news that the hard hat -- that quintessential American symbol of on-the-job toughness -- is turning 100 years old this year.

More than 20 million Americans wear them at work each day. Another six million are sold each year. In some circles, they're a status symbol.

In fact, one study showed that hard hats are such a key to status on some job sites that during Boston's Big Dig project around 2010, workers who weren't required to wear them did so anyway -- even while they declined to wear respirators or hearing protection, which were much more practical and would have protected them from actual dangers.

That comes from a paper by Beth Rosenberg, an associate professor at Tufts University School of Medicine, which was quoted in a New York Times article celebrating the hard hat's centennial.

"Dr. Rosenberg said hard hats had become associated with masculinity and patriotism," the Times reported. The term 'hard hats' even became shorthand for working people with a conservative patriotism."

The hard hat traces its roots to U.S. soldiers in World War I; a returning doughboy named Edward W. Bullard came up with the idea of designing a helmet similar to the one he'd worn in the military in France for construction workers back home.

The first ones were made of "steamed canvas and leather (metal was too expensive)," and painted black.

But more recently, as helmets have evolved, there's a color scheme:

  • White hats: usually worn by a "supervisor, an engineer or a quality-assurance agent," according to the Times. I checked this and the rest of the colors below against the website Hard Hat Expert, which honestly seems a bit more authoritative in this context. 
  • Green hats: "Safety officers or inspectors"
  • Yellow hats: "Workers who operate any heavy machinery or earth movers ... or employees doing general construction labor"
  • Brown hats: "Workers who do any form of welding or other high-heat jobs."
  • Orange hats: "Road construction workers ... [plus] new hires and site visitors."
  • Blue hats: "Electricians and carpenters."
  • Red hats: "Firefighters [and] other employees with emergency training."
  • Grey hats: "These are most often issued to visitors on the work site."
  • Pink hats: "These hard hats tend to be most popular with female workers. Certain businesses may also try to discourage forgetfulness by issuing a pink hat to any worker who accidentally left their own hard hat at home."

Many of these colors have different meanings at different job sites and while working for different companies. However, "white hats means supervisor" seems to be the common denominator across all job sites.

That's why I think that color -- and its significance beforehand -- is interesting.

I'll cop to it myself: before I read about this today, I don't think I knew about the color scheme.

And if you're like me, it means there's a basic thing (looking out for white hats, because that means "the boss") that 20 million of our fellow Americans have their eyes open for each day at work, and we didn't know  

I wonder what other basic things we know nothing about.