How CAPTCHAs work

This three-minute video explains how those annoying “I’m not a robot” reCAPTCHA checkbox tests work. It turns out the checkbox itself is not the test at all, but rather it’s your mouse movements and browsing history that give away your humanity. The video is full of surprising facts about these “completely automated public Turing tests.” For instance, I learned spammers pay workers as as little as $1.00 per thousand tests to solve CAPTCHAs. — MF