Captcha Overview


<!-- BEGIN Captcha Captcha1 -->
<canvas id="Captcha1Picture" width="{Width}" height="{Height}"></canvas>
<!-- END Captcha Captcha1 -->
<input id="TextBox1" value="{TextBox1}" name="{TextBox1_Name}">




The term "CAPTCHA" is a contrived acronym for "Completely Automated Public Turing test to tell Computers and Humans Apart."

It 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. Thus, it is sometimes described as a reverse Turing test, because it is administered by a machine and targeted to a human, in contrast to the standard Turing test that is typically administered by a human and targeted to a machine. A common type of CAPTCHA requires that the user type letters or digits from a distorted image that appears on the screen.

See also

Captcha Reference