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A method for soliciting help from the general public in order to assist large, text-to-computer projects that digitize thousands of old books. Regular CAPTCHAs are the distorted words found on websites that users type back in to validate that they are humans and not computers. Every day, hundreds of millions of CAPTCHAs are entered, creating a huge pool of human resources to draw from.

In a reCAPTCHA system, the images of words that the optical character recognition (OCR) program cannot decipher are dispersed to several people in the form of a CAPTCHA to get a consensus. Originally developed by Carnegie Mellon University, reCAPTCHA was acquired by Google in 2009. For more information or to get reCAPTCHA code, visit See OCR and CAPTCHA.

A known word (left) is always sent with the bad word so that the reCAPTCHA serves as a valid CAPTCHA. After several people enter the same text for the bad word, the system considers the word properly converted.

In 2014, Google introduced No CAPTCHA human authentication. Most of the time, users only have to click the box. If the system fails to authenticate, a test is presented such as having to select all the animal pictures from a group that are the same species as the given image.
References in periodicals archive ?
Four years ago, Google turned reCAPTCHA into a system for training AI
Vicarious' RCN is able to crack reCaptchas 6 the advanced version of Captcha 6 with an accuracy rate exceeding 66 percent, notes the report.
2: ReCAPTCHA, Clikable CAPTCHA, Asima, Drwing CAPTCHA and accCAPTCHA.
However, the introduction of No Captcha Recaptcha, in 2014, was a stepping stone to something greater.
After the development of reCAPTCHA, multiple complex systems evolved from the basic ideology and next came the Image CAPTCHA system.
Un ejemplo de ello es reCAPTCHA, un servicio antirobot gratuito empleado por Google para corregir los errores en los OCRs empleados para el analisis de los textos de los libros digitalizados en Google Libros y que permite a millones de personas que diariamente validan accesos a servicios en la web reinterpretar cada dia caracteres no legibles por los OCRs en mas de cien millones de palabras dudosas y mejorar asi la digitalizacion (Vercelli, 2010).
The removal of the Recaptcha security feature for individual bookings, effective from November 1.
Arabic reCaptcha, which will commence by early 2014, will continue for two-and-a-half years, Dr Hassan Obaid Al Muhairi of Khalifa University told Khaleej Times.
ICT Fund, an initiative by the Telecommunications Regulatory Authority (TRA), which supports the national ICT sector through financing innovative projects in the UAE, has signed an agreement with Khalifa University to fund a new Research & Development (RD&) project called reCaptcha.
Irish budget carrier Ryanair (LSE:RYA) on Friday said that its improved Internet security provided by the reCAPTCHA feature on its website is a success.