What is a CAPTCHA and Why is it Important?

CAPTCHA (Completely Automated Public Turing test to tell Computers and Humans Apart) is a security measure designed to prevent bots from abusing online services. By implementing a CAPTCHA, you can significantly reduce automated login attempts and spam submissions.

Steps to Create a Simple CAPTCHA

Here’s how you can build a basic CAPTCHA system in PHP to protect your website:

Step 1: Generate a Random Code

Create a random string of characters to serve as the CAPTCHA text. Store this in a session for later verification.

Step 2: Render the CAPTCHA as an Image

Use PHP’s GD library to create an image displaying the CAPTCHA code.

Step 3: Add the CAPTCHA to Your Form

Embed the CAPTCHA image in your form and provide an input field for users to enter the code.

Step 4: Validate the CAPTCHA Input

Compare the user’s input with the stored CAPTCHA code in the session. If they match, allow the user to proceed.

Enhancing the CAPTCHA

To make your CAPTCHA more effective and user-friendly, consider the following enhancements:

• Add random distortion or background noise to the image.
• Use multiple fonts and colors for the CAPTCHA text.
• Implement audio CAPTCHA for accessibility.
• Limit the number of CAPTCHA attempts per session.