CaptchaSecurityImages php验证码 Link: http://www.white-hat-web-design.co.uk/articles/php-captcha.php

he reCAPTCHA PHP Library provides a simple way to place a CAPTCHA on your PHP website, helping you stop bots from abusing it. The library wraps the reCAPTCHA API. To use reCAPTCHA with PHP, you can download reCAPTCHA PHP library. You will only need o

Captcha of rectangles for registration form.