Whenever I open Instagram these days, it feels like I’m being watched. The minute I follow a new person or double tap a landscape or cat pic, the photo-sharing app—to which I’ve long been addicted—picks up on it and starts showing me remarkably similar images. It’s almost creepy. As it turns out, Instagram’s algorithms are indeed keeping an eye on me, busily drawing a complex map of my likes, follows, and other in-app behavior, and that of the people I follow as well. As the app learns, its Explore tab gets better at recommending photos and videos to me. I can’t help but take the bait. Next thing you know, I’m barreling down some new visual rabbit hole and following six more people. The Explore tab is essentially one giant recommendation engine. But the ever-evolving methodology Instagram uses to sort through one of the world’s largest networks of photographs, comments, and likes is far more complex than your standard, “If you like that, you’ll like this” logic. And, surprisingly, Instagram says that despite the image recognition capabilities of parent company Facebook, there’s no machine vision involved. Read more at Fast Company.