A CAPTCHA is a program that can tell whether its user is a human or a computer. You've probably seen them — colorful images with distorted text at the bottom of Web registration forms. CAPTCHAs are used by many websites to prevent abuse from "bots," or automated programs usually written to generate spam. No computer program can read distorted text as well as humans can, so bots cannot navigate sites protected by CAPTCHAs.
reCAPTCHA is digitizing old NYTimes, and every time a user fills out a CAPTCHA you are helping. Logged in users do not need to fill out a CAPTCHA, but the vast majority of posts are made from users who are not logged in. Combining the total number of replies and topics, we can estimate the total number of successful CAPTCHAs at 799,087.
That's quite a number. If we figure an average of 10 seconds per CAPTCHA, that equals out to:
55.5 Work Weeks (40 Hour)
It would have taken a human being, working 40 hours a week, over a year to do the same amount of reCAPTCHAs. That's kind of cool to think about. I wonder how many days/weeks of NYTimes we've helped digitize.