You’ve probably heard of a CAPTCHA. In case you haven’t you can hear about it from us. Now here we have another form of a Captcha which apart from performing its deemed function of protecting a system from bots, also helps in digitizing books, newspapers and radio shows.

reCAPTCHA was developed at Carnegie Mellon University and it uses CAPTCHA to help digitize the text of books while protecting websites from bots attempting to access restricted areas. reCAPTCHA is currently digitizing text from the Internet Archive and the archives of the New York Times.

reCAPTCHA uses images of words that Optical Character Recognition softwares fail to recognize and uses them as CAPTCHAs for humans. Along with the words the system doesn’t know, it also checks a word that it knows. So under the assumption that a user who correctly identifies a word from a pair, will also identify the other, this system goes about digitizing books. It takes a number of options on the same word and finds the appropriate answer with higher confidence.

reCAPTCHA is presently delivering over 30 million words to different websites and encourages more users to apply it on their websites. Popular websites that use this system are Facebook, StumbleUpon, and Twitter.

Learn more about reCAPTCHA here.