In this we video we are going to tell you about Captcha, What is Captcha? , Why website use Captcha?, when did Captcha use for first time? Read for details A CAPTCHA (Completely Automated Public Turing test to tell Computers and Humans Apart) is a challenge-response system test designed to differentiate humans from automated programs. A CAPTCHA differentiates between human and bot by setting some task that is easy for most humans to perform but is more difficult and time-consuming for current bots to complete. The term CAPTCHA was first used by computer scientists at Carnegie Mellon University in 2000. Frequently, a CAPTCHA features an image file of slightly distorted alphanumeric characters. A human can usually read the characters in the image without too much difficulty. A bot program is able to recognise that the content contains an image , but it has no idea what the image is. To accommodate the visually-impaired, some CAPTCHAs use audio files. In such a system, the human listens to a series of letters or short words and types what he hears to prove he is not a bot.