What is the CAPTCHA Project?

CAPTCHA refers to a category of information technologies used to ensure that a human rather than a computer is making an online transaction. It is an acronym for Completely Automated Turing Test to Tell Computers and Humans Apart and patented by Carnegie Mellon University. It is a challenge response test used in computing to determine whether the user is a human. A typical CAPTCHA requires a user to type the letters of a distorted image, sometimes with the addition of an obscured sequence of letters or digits that appear on the user’s screen. The origin of the CAPTCHAs was to counter the characteristics of software agents (bots) that automatically fill up web forms as individual users.