Free AI training.

Back in the day they’d give you two words in wonky text. One word they knew, one they needed your help with to improve their ability to scan books and documents into a digital forget. They didn’t explicitly tell you what the purpose was, and wouldn’t tell you which is which, but if you knew what to look for you could figure out which is the “unknown” word and just put whatever you wanted into the captcha for it to mess with their dataset. Good times.