Every day, you use apps and services that were carefully crafted by teams of professional designers to deliver the best user experience possible. At least, that’s the idea. However, if you’ve ever found it easier to sign up for an account than it is to cancel it, you’ve stumbled onto a dark pattern. And over the next several weeks, WIRED is going to dissect common examples across online shopping, social media, search, and more.

The term “dark patterns” was first coined by UX specialist Harry Brignull to describe the ways in which software can subtly trick users into doing things they didn’t mean to do, or discouraging behavior that’s bad for the company. When you want to unsubscribe from a mailing list, but the “Unsubscribe” button is tiny, low-contrast, and buried in paragraphs of text at the bottom of an email, it’s a strong sign the company is putting up subtle roadblocks between you and cancellation.

The button to buy an item that’s on sale, on the other hand, is large, bright, and at the top of the email. There’s no hiding that one.

Not all dark patterns are designed maliciously, and some UX designers might not even be aware that they’ve built a system that’s tricking users. In many cases, designers might just be doing what works. But being cognizant of how app design plays on human biases is key to avoid falling victim to dark patterns.

UX Design Leads Your Behavior, and That’s (Usually) a Good Thing

Websites and apps rely on design language to direct users on how to accomplish the task they want to do. A red circle lets you know there’s a notification that needs your attention. Click on an X icon to close whatever you’re working on. If a user can’t immediately understand how an app works, they’re likely to get frustrated and stop using it. So, to give users a positive experience, UX designers build their software to be as intuitive as possible.

“If you don’t feel successful using a tech tool, you won’t continue using it,” says behavior scientist and author of Tiny Habits BJ Fogg. “Look at all the apps on your phone—all those apps you used once and never again. They failed to move you forward to time number two, much less create a habit. Those apps didn’t help you feel successful.”

Take an app like Duolingo, for example. It allows you to sign in via services like Google or Facebook, and after a few basic setup questions, immediately drops into a lesson. Compare this to other apps like Rosetta Stone that require a several-step-long process to create an account, then asks users to pick from a selection of lesson plans and sign up for a trial account, which includes providing payment information before they’ve even tried the app.

“Duolingo does a pretty good job of helping people feel successful. Without that, I would predict Duolingo wouldn’t be the number one language-learning platform,” says Fogg, who says he uses the app every day to learn Hawaiian.

Since every tap is a chance for a user to get frustrated and leave, developers have an interest in learning and manipulating the micro-decisions that users make that can lead to enjoying or hating an app.

When Design Goes Bad

The trouble comes when the company that makes an app or site has different priorities than the person using it. For example, when you sign up for a monthly subscription service, most companies will make that process easy. However, if you want to cancel, the company might put a couple of speed bumps in the way to discourage you. Sometimes this can be subtle, like making the “Never mind, I’d like to stay” button bright and colorful while making the “Yes, I really want to cancel, let’s get on with it” button more subtle.