The double life of Captcha anti-spam tests
Back Posted on 16 Jan 2017
Everyone's been challenged by a reCaptcha anti-spam test at some point. It's employed on forms across the internet to help prevent spam reaching website owners.
But did you know those cryptic letter identification tests to prove you are human are actually real objects that computers need help to understand?
Solving them helps computers learn skills that help preserve books and improve maps:
Every time our CAPTCHAs are solved, that human effort helps digitize text, annotate images, and build machine learning datasets. This in turn helps preserve books, improve maps, and solve hard AI problems. 
That's all kinds of clever, devious and helpful all at the same time.
Read more about reCaptca at: https://www.google.com/recaptcha/intro/index.html
And the new and improved noCaptcha at: https://security.googleblog.com/2014/12/are-you-robot-introducing-no-captcha.html