reCAPTCHA is a free CAPTCHA service that helps to digitize books, newspapers and old time radio shows.
About 200 million CAPTCHAs are solved by humans around the world every day. In each case, roughly ten seconds of human time are being spent. Individually, that's not a lot of time, but in aggregate these little puzzles consume more than 150,000 hours of work each day. What if we could make positive use of this human effort? reCAPTCHA does exactly that by channeling the effort spent solving CAPTCHAs online into "reading" books.... More Info »
To archive human knowledge and to make information more accessible to the world, multiple projects are currently digitizing physical books that were written before the computer age. The book pages are being photographically scanned, and then transformed into text using "Optical Character Recognition" (OCR). The transformation into text is useful because scanning a book produces images, which are difficult to store on small devices, expensive to download, and cannot be searched. The problem is that OCR is not perfect.
Link to official reCAPTCHA site
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anti-spam captcha
reCAPTCHA was added by Sedoe in
Apr 2011 and the latest update was made in
Nov 2016. The list of alternatives was updated Aug 2018 There is a history of all activites on
reCAPTCHA in our Activity Log.
It's possible to update the information on reCAPTCHA or report it as discontinued, duplicated or spam.
