Why we have to fill CAPTCHA or RECAPTCHA

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Why we have to fill CAPTCHA or RECAPTCHA


Why RECAPTCHA or CAPTCHA introduced  

We know that reCAPTCHA checks whether the information is submitted by a "bot" or Person. But why we need to fill reCAPTCHA. Let's take an example of railway reservation site where many  user visiting the site at the same time, the time taken by any user is about 5 min to fill information ,but someone is good in programming develops a code that fills the information itself in very less time.So it questioned many sites that how to check whether visitor is Person or "bot". To prevent this the concept of CAPTCHA or reCAPTCHA was introduced.


What is CAPTCHA

CAPTCHA is short form of Completely Automated Public Turing test to tell Computers and Humans Apart. reCAPTCHA is free service from Google to protect websites from spam and abuse. A "CAPTCHA" is a turing test to tell human and bots apart. It is easy for humans to solve , but hard for "bots" and other malicious software  to figure out. So if we add reCAPTCHA to our site, we can block automated software.





Which codes are used in CAPTCHA

In CAPTCHA user have to fill appropriate words displayed  by CAPTCHA but  words being displayed are different in shape,size,color etc. that human can read easily but is nearly impossible for "bots". 

What is reCAPTCHA 

CAPTCHA displays different meaningfulness word , but in reCAPTCHA it displays meaningful words. but how those words are generated, Many books were scanned by OCR and word that is deciphered differently by both  OCR programs or that is not present in English dictionary is marked as "suspicious" and converted into a CAPTCHA.







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