What is CAPTCHA?

I used CAPTCHA many times in developing different Web Applications and even used in many websites but didn't know the formal name. I used to identify it as Word Verifier or code for Word Verification. Whatever! Now I learned that the formale name is CAPTCHA!

While i was looking into Online for more information on CAPTCHA see few interesting URL i got sharing with you all below:

CAPTCHA from Wiki (http://en.wikipedia.org/wiki/Captcha)
Breaking Captchas without using OCR (http://www.puremango.co.uk/cm_breaking_captcha_115.php)
Breaking a Visual CAPTCHA (http://www.cs.sfu.ca/~mori/research/gimpy)
The CAPTCHA Project (http://www.captcha.net)
PWNtcha - Captcha decoder (http://sam.zoy.org/pwntcha)