Re CAPTCHA

Re CAPTCHA

reCAPTCHA is a user-dialogue system originally developed by Luis von Ahn, Ben Maurer, Colin McMillen, David Abraham and Manuel Blum at Carnegie Mellon University's main Pittsburgh campus. It uses the CAPTCHA interface, of asking users to enter words seen in distorted text images onscreen, to help digitize the text of books, while protecting websites from bots attempting to access restricted areas. On September 16, 2009, Google acquired reCAPTCHA. reCAPTCHA has worked on digitizing the archives of The New York Times and books from Google Books. As of 2009, twenty years of The New York Times had been digitized and the project planned to have completed the remaining years by the end of 2010.

The reCAPTCHA service supplies subscribing websites with images of words that optical character recognition (OCR) software has been unable to read. The subscribing websites (whose purposes are generally unrelated to the book digitization project) present these images for humans to decipher as CAPTCHA words, as part of their normal validation procedures. They then return the results to the reCAPTCHA service, which sends the results to the digitization projects.

The system has been reported as displaying over 100 million CAPTCHAs every day, and among its subscribers are such popular sites as Facebook, TicketMaster, Twitter, 4chan, CNN.com, and StumbleUpon while Craigslist began using reCAPTCHA in June 2008. The U.S. National Telecommunications and Information Administration also used reCAPTCHA for its digital TV converter box coupon program website as part of the US DTV transition.

reCAPTCHA's slogan is "Stop spam, read books."