reCAPTCHA- A Great Initiative

Just thought I’d write up a quick post regarding reCAPTCHA – A free CAPTCHA service that can be implemented on any site that not only stops spammers, it digitizes books, newspapers and old time radio shows at the same time! The idea is that people waste time every day solving captchas (about 200 million CAPTCHAs a day), and while on an individual level you might only be wasting 10 seconds or so each time, the combined time spent is over 150,000 hours each day.ReCAPTCHA takes that time and effort and makes constructive use of it.

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 problem is, a page scanned from an old book cannot be parsed accurately by software – Enter reCAPTCHA! When the parsing software comes to a word it can’t read, reCAPTCHA will send it as a captcha to a random human filling out a form online. By solving the captcha, that person has “parsed” the word. You might wonder how the captcha can be solved if the computer doesn’t know the right anwser – Each word that cannot be parsed correctly by software is given to a user in conjunction with another word for which the answer is already known. The user is then asked to read both words. If they solve the one for which the answer is known, the system assumes their answer is correct for the new one. If five other users answer the same captcha identically, then the system can assume with high confidence that the answer is correct.


Pretty awesome if you ask me. They’ve even made it really easy to implement on your sites with ready to use PHP snippets and a plugin for WordPress and Mediawiki. We’ve been using it company wide for all our captcha needs. We hope there’s more constructive initiatives like this in the future!

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