Don't you just love Captchas? CAPTCHA is an acronym for Completely Automated Public Turing Test.
CAPTCHA - was coined in 2000 buy carnegie Mellon university. first CAPTCHA used by yahoo
Helps us :
Preventing Comment Spam in Blogs.
Protecting Website Registration
Preventing Dictionary Attacks
Search Engine Bots
Worms and Spam
These systems make it impossible for users with certain disabilities to create accounts, write comments, or make purchases that is, CAPTCHAs fail to properly recognize users with disabilities as human.
Few toughest Captchas here..Try :-)!