CAPTCHA stands for “Completely Automated Public Turing test to tell Computers and Humans Apart“. :O
According to Wikipedia
CAPTCHA is a type of challenge-response test used in computing to ensure that the response is not generated by a computer. The process usually involves one computer (a server) asking a user to complete a simple test which the computer is able to generate and grade. Because other computers are unable to solve the CAPTCHA, any user entering a correct solution is presumed to be human.
here is the link. Go and read by yourself. 🙂
I was asked to integrate a CAPTCHA for the web portal we are working on. Luckily I found a very helpful project called reCAPTCHA which is originally developed at Carnegie Mellon University.
Here is a part of my test project to integrate a CAPTCHA to a form. Just have a look … 🙂