Mon, 14 Apr 2008 15:00:00 GMT
Many Web forms these days feature a Completely Automated Public Turing test to tell Computers and Humans Apart (CAPTCHA) as an effort to stop people from setting up computers to automatically fill in Web forms. A typical CAPTCHA is an image with some numbers and letters in it with distortion and/or background noise, and a Web form input field where you are to enter the numbers and letters from the image. This article investigates three CAPTCHA applications that you can use on a PHP Web site.