An image outage on Facebook, Instagram, and WhatsApp showed how Facebook's AI automatically tags your photos behind the scenes.

The tags sparked anger and amusement on Twitter, as people shared how their photos were interpreted — or misinterpreted.

On Twitter, people shared some of their tags, which included the mundane ("one person, beard") and the disconcerting ("people standing, hoes, and indoor").

Visit Business Insider's homepage for more stories .

An image outage across Facebook, Instagram, and WhatsApp gives a behind-the-scenes look at how Facebook's AI sees your photos.

The outage, which started on Wednesday and affected Facebook's 1.5 billion-plus daily active users and rendered Instagram all but unusable, stopped social-media images from loading and left in their place descriptions like: "image may contain: table, plant, flower, and outdoor" and "image may contain: tree, plant, sky."

(Or maybe that's just my feed.)

This is the kind of thing a lot of people saw on Facebook, Instagram, and WhatsApp instead of their actual photos. Screenshot/Matt Weinberger

These descriptions, or tags, show how Facebook's artificial intelligence interprets images.

On Twitter, people shared screenshots of how their photos were tagged. "To be fair, 'one person, beard' is pretty much a spot-on description of me," Zack Whittaker, an editor at TechCrunch, wrote.

So, what's going on?

Facebook automatically scans all photos on the social network with facial- and image-recognition software powered by AI to detect who or what is being pictured.

This is then used in the company's accessibility efforts to describe photos to people who are blind or otherwise visually impaired, and who are accessing the site via a screen reader.

In short, Facebook uses machine learning to automatically interpret photos, then reads this interpretation aloud to blind users. The photo outage meant that we got an in-your-face look at those interpretations, too.

At times, it appeared the AI incorrectly tagged the photo, as in the case of the Fortune reporter Danielle Abril's where the photo description read: "5 people, including Danielle Abril, people smiling, people standing, hoes and indoor." Hopefully there was a gardening tool in the photo — we've reached out to Abril but did not immediately hear back.

So while there could be a benign explanation here, it's still a stark reminder of just how much data Facebook is gathering at all times, even when we don't realize it's happening. Thanks to its increasingly sophisticated AI technology, Facebook can even gather information from something as innocuous as a vacation photo.

"Once something is legible, of course, it becomes easy to store, analyze, and extract data from. It's only when the system breaks down, like today, that we realize it's happening at all," James Vincent of The Verge, wrote.