CAPTCHA

Completely Automated Public Turing test to tell Computers and Human Apart..

It s kind of word verification test... to differentiate human and computers.

Reason for having  CAPTCHA:

• To prevent 1)malicious attacks

                            2)Spammers

• To avoid automated software bots..

(Automated software bots-computer automatically created huge no. of large requests to server which in turn cause, degrade the server quality)

Various forms of  CAPTCHA:

• It is distorted  or randomly  stretched characters ..

• It is rely on images also, four images present in that three of them contain animal picture, one contain flower. We have to choose it.

• Another audio challenge which contains some sound with noisy effect..

Human beings only able to identify patterns of CAPTCHA

Pros:

One Artificial intelligence algorithm is found   until to train the real intelligence to machine to break

CAPTCHA

Applications of CAPTCHA:

1)Online polls

2)Registration forms

3)Free account creation process in Gmail,Ymail,hotmail etc