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The people you barely know—your dry cleaner, for example, or the guy you regularly see sweating next to you on the treadmill at the gym—are "consequential strangers," and they're actually important to your mental well-being, say the authors of a new book. According to Melinda Blau, co-author of Consequential Strangers: The Power of People Who Don't Seem to Matter... But Really Do, there's a "relationship continuum" from strangers to besties, and a good chunk of people fall into the middle-ground. Many of those 800 plus friends you've racked up on Facebook? Yep, they're consequential strangers. As are the countless somewhat-familiar people we see on a regular basis, all of whom supposedly "make us feel grounded in the world."

In a city of more than eight million people, you probably have more of these "strangers" in your life than people living in other parts of the country. There's your housekeeper (if you can afford to have one); your doorman (see previous); your bikini waxer (if you're a woman; well, maybe if you're a man, too); the homeless guy who you sometimes give change to; the owners of the dogs your own dog plays with; the dude who you buy a paper from every morning (assuming you still pay for a newspaper, of course); and the guy behind the counter at your local deli/bodega, whom you know nothing about, but who knows that you like your morning coffee with a little bit of skim milk and one packet of Equal (unless it's summer, that is, in which case he promptly fixes you an iced coffee). You see? They're everywhere!

But why do these people matter so much? The paradox, according to Blau, is that while we think our real friends are the most important people to us, it's these fringe acquaintances who can potentially give us "exposure to the most novel experiences." (Yet another explanation to give to friends who complain they can't meet anyone to date when they just keep hanging out with the same close-knit group of people.) If it wasn't for your bikini waxer, for example, how would you know what it's like to immigrate to the U.S. from Russia? And if it wasn't for the dude at the deli with the poster of Dhaka stapled to the wall behind him, you wouldn't have known that Dhaka happens to be the capital of Bangladesh, now would you?

But this all begs the question: What, then, is an inconsequential stranger? A one-night stand? A random Twitter follower? Paris Hilton? That remains unclear. In the meantime, we're going to get a little "more grounded" and head over to the deli for another "novel experience." And we might even pick up a cup of coffee while we're at it.

The Importance of Consequential Strangers [Time]