The world today is filled in with enormous amount of innovation and technology, Internet is thus stated to be one of the most beneficial part awarded to the society ,but web security is the crucial issue to be considered to ensure this a concept called CAPTCHA is developed. CAPTCHA stand for Completely Automated Public Turing test to tell Computer and Human Apart this is a technique that was initialized in 1997 and was developed in 2000. The term "CAPTCHA" was coined by Luis Von Ahn, Manuel Blum, Nicholas J. Hopper (all of Carnegie Mellon University, and John Langford (then of IBM). CAPTCHA is an automated Turing test that can help us to generate and test grades which human can easily understand and pass while bots cannot. In this paper we are analyzing and using the concept of Audio ReCAPTCHA.

1. Haichang Gao, Honggang Liu, Dan Yao, Xiyang Liu,An audio CAPTCHA to distinguish humans from computers
2. E. Athanasopoulos and S. Antonatos. Enhanced captchas: Using animation to tell humans and computers apart. In IFIP International Federation for Information Processing, 2006.
3. L. von Ahn, M. Blum, J. Langford, "Telling Humans and Computers Apart Automatically Communications of the ACM", vol. 47, no. 2, pp. 57-60, Feb. 2004.
4. J. of G. R. in C. Science and J. 2012,"Survey on CAPTCHA systems".
5. Elie Bursztein, Steven Bethard, Celine Fabry, John C. Mitchell, Dan Jurafsky, How Good are Humans at Solving CAPTCHAs
6. L. von Ahn, M. Blum, N. Hopper, and J. Langford. CAPTCHA: Using hard AI problems for security. In Eurocrypt, 2003

Captcha Recaptcha Audio digitization