How to Create CAPTCHA Protection using PHP and AJAX

CAPTCHA is a simple test to determine if a user is a computer or a human. It is used to prevent spam abuse on the websites. So if you use CAPTCHA on your web site forms, this can help in stopping some bots and making life harder for other bots in accessing or using your forms. The goal of this tutorial is to demonstrate how to make your own simple CAPTCHA protection using PHP and AJAX technologies.