Showing posts with label captcha. Show all posts
Showing posts with label captcha. Show all posts

Thursday, July 26, 2007

CAPTCHA

Defeat spammer and bots, the smart way!

CAPTCHA is an acronym for “Completely Automated Public Turing test to tell Computer and Human Apart”. A project of the Computer Science Department of Carnegic Mellon University (trade mark owned by Cernegic), CAPTCHA is a mechanism to tell humans and computers apart, automatically. In short, CAPTCHA is an application that can generate and grade tests that a human can pass, but are difficult (though not impossible, as we will see later) for a computer to pass.
The most common type of CAPTCHA is a challenge-response kind of a system. The application generates a distorted image of text characters, numbers, etc, that are difficult for a computer program to understand, but can be understood and read by a human. An example of CAPTCHA is the image below taken from wikipedia.org.

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