How companies subtly trick users online with 'dark patterns'

An "unsubscribe" option that's a little too hard to find. A tiny box you click, thinking it simply takes you to the next page, but it also grants access to your data. And any number of unexpected charges that appear during checkout that weren't made clearer earlier in the process.

Countless popular websites and apps, from retailers and travel services to social media companies, make use of so-called "dark patterns," or gently coercive design tactics that critics say are used to manipulate peoples' digital behaviors.

The term "dark patterns" was coined by Harry Brignull, a U.K.-based user experience specialist and researcher of human-computer interactions. Brignull began noticing that when he reported to one of his clients that most test subjects felt deceived by an aspect of their website or app design, the client seemed to welcome the feedback.