Question about CAPTCHA

Certain captcha's are unreadable fro two reasons:

1. The letters are tested by OCR software. If the software can recognise the letters then you have to distort them further. Sometimes this is taken a step too far.
2. Like varkey pointed out with recaptcha the second words is a something that OCR software could not recognise. As a human you probably recognised the word. So when you enter the correct word you are basically helping the words of OCR move a step forward.
 
^true, captcha system works in that way.. only one word is enough. Idea behind that is..human can read only one and other is to confuse the automated captcha readers. Some what if you read both word properly and enter, then captcha system will not allow to go throug :), since it expects only one to answered properly...
 
I couldn't see anyone with the exception of varkey giving an appropriate answer so here's why -

What is reCAPTCHA?

When Captcha was introduced, it was done primarily for the purpose of distinguishing people from bots. Later, the inventor decided to put the time (~ 10-30 secs) taken by millions of us to some good use. He decided to help out in the digitizing old books. Most of the books are bad and out of shape. OCR can read most of the characters and the ones it is unable to read are generally the 2nd word.

How this works is, as it is already mentioned above, the 1st word is known to the software. The 2nd word is given to more than 1 person, say 20 or 50 or maybe even 100. After getting the results, it compares and picks the word that is guessed most assuming it to be the correct word.

A win-win situation for both! :)
 
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