What is CAPTCHA - The Complete Explanation

       

                     Ever wondered what CAPTCHA means??

What is the difference between reCAPTCHA & CAPTCHA?

CAPTCHA is "Completely Automated Public Turing Test To Tell Computers and Humans Apart". This will test and analyse whether the user is a human or computer and so prevents spam and automated data downloading. It typically asks the user to write down a combination of alphabets/numbers from an image. The text cannot be copy pasted from the image, thus preventing computers any access.
Below pic is an example of CAPTCHA: This user identification procedure has received many criticisms, mostly from the disabled people and also from other people who feel that their everyday work is slowed down to sort out the words that are difficult to read.Do you known something! For an average person it takes approximately 10 seconds to solve a typical CAPTCHA. Any program that passes the tests generated by a CAPTCHA can be used to solve a hard unsolved AI (Artificial Intelligence) problem.                 What is reCAPTCHA? reCAPTCHA is a free service that protects your website from spam and abuse. reCAPTCHA uses an advanced risk analysis engine and adaptive CAPTCHAs to keep automated software from engaging in abusive activities on your site. It does this while letting your valid users pass through with ease.reCAPTCHA offers more than just spam protection. Every time our CAPTCHAs are solved, that human effort helps digitize text, annotate images, and build machine learning datasets. This in turn helps preserve books, improve maps, and solve hard AI problems. Easy for People.   Hard for Bots                Purposefully designed. And actively aware. reCAPTCHA knows when to be easy on people and hard on bots. Our easy CAPTCHAs are a breeze for legitimate users.   This idea an interesting application of CAPTCHA. There are several projects of converting books to the ebook version. One method is to scan the books and use OCR software to convert image of text to actual text. But somebody has to validate whether the conversion is successful. Luis von Ahn, Ben Maurer, Colin McMillen, David Abraham and Manuel Blum at Carnegie Mellon University developed reCAPTCHA to help in this problem. Instead of random texts in CAPTCHA, actual texts from scanned books are shown. The user writes the digital text. This is used to validate each word from several users.                                                                          Check out this video Guys!                                                                                                                                                                                                                                                                                                                                                                        - sandeep simeon