It's the end of the month, and you're furiously uploading receipts to submit to your employer for reimbursement. It's been a busy few weeks — too many Lyft trips to count — so you have a lot to expense. Thankfully, the online reporting platform you use employs some kind of fancy schmancy AI to automatically detect how much you spent and where you spent it, changing emailed and crumpled paper receipts into digital reports with ease.

Or, so you think, anyway. But like the famed 18th century Mechanical Turk that wowed people around the world with its seeming ability to play chess, things aren't exactly what they seem. Your boss, it turns out, might not be the only one seeing your expense reports.

It's not too difficult to see behind this particular curtain, but in the case of Amazon's Mechanical Turk, you first have to know the curtain exists. Launched in 2005, the online service bills itself as "a marketplace for work that requires human intelligence."

What this means in practice is that human beings can sign up to complete menial tasks online for as little as a few pennies each. But just who are these anonymous workers, and what is it they are actually doing?

An unexpected place

One company that, until Nov. 23, used Mechanical Turk workers in a limited capacity was Expensify, which makes expense management software. On Nov. 22, a Twitter user posted that she was able to see "someone’s Uber receipt with their full name, pick up, and drop off addresses" due to her role as a Mechanical Turk worker.

Tweet may have been deleted

Sensing a possible PR disaster, the company quickly backtracked — issuing a blog post detailing exactly when and how it relied on MT workers to decode uploaded receipts. And, more importantly, that it would stop.

"Needless to say, we were caught off guard by the sheer scale of concern raised by dipping our toe into the Mechanical Turk waters after so many years of absence, and we found the water to be very, very cold," read the post. "We have already pulled our toe back out and have no active Mechanical Turk jobs at this time."

And while that, more or less, closed the book on this Expensify-specific concern, it opened up another question entirely: Just who, exactly, are the people churning through menial online tasks for pennies?

Your friendly, neighborhood Mechanical Turk

The type of person who looks to the internet for a little extra spending cash turns out to be, well, pretty much like everyone else. A popular Mechanical Turk message board, Turker Hub, makes this clear.

One section dedicated to new member introductions includes anecdotes about a pay cut in the family driving one MT worker to look for extra income, a 39-year-old housewife with children who enjoys knitting, and a stay-at-home mom with a special needs kid. Another forum member notes that he or she has been "turking" for a year and half, is a Libertarian, has dreadlocks, and likes animals more than people.

"I'm pretty new to the whole taking mturk seriously situation," reads one such post. "I've been turking for about 5 hours a day for the past two and a half weeks or so with the ultimate goal of making enough to support myself from home."

One example MT task listing makes it clear just how difficult succeeding at that goal could be. "Look at the photo below," it reads. "Type the 17-digit VIN you see in the image. If the VIN is not 17 digits, do not complete this HIT."

This task pays $.03.

The extremely limited per-item payout obviously isn't a deterrent to the untold number of people Turking their way through each day. And on the face of it, those behind-the-scenes workers appear to be nothing more than a cross-section of the population, all completing "human intelligence tasks" with the hope of fulfilling that age-old promise of making money using nothing more than a home computer.

Whether that promise ends up having more substance than the original Mechanical Turk — a elaborate hoax powered by human labor — is anyone's guess. That being said, it doesn't look to be going anywhere: something to keep in mind the next time you're online, observing the magic of the human-powered internet at work.