How to implement captcha in php?

This is the tutorial that can implement the captcha in the PHP form and verify whether the user is a real user or a robot user. So just make the below files and set them to your form, which can attach the captcha.

Step 1)

Make a PHP file and put the below code there.

<div>
     <img src="captcha_code.php"/>
     <input name="captcha_code" type="text" id="captcha_code" placeholder="Enter Captcha Code">
</div>

Step 2)

Make another file named "captcha_code.php." Put the below code in that file.

<?php
session_start();
$random_alpha = md5(rand());
$captcha_code = substr($random_alpha, 0, 6);
$_SESSION["captcha_code"] = $captcha_code;
$target_layer = imagecreatetruecolor(70,30);
$captcha_background = imagecolorallocate($target_layer, 148, 7, 10);
imagefill($target_layer,0,0,$captcha_background);
$captcha_text_color = imagecolorallocate($target_layer, 255, 255, 255);
imagestring($target_layer, 8, 8, 8, $captcha_code, $captcha_text_color);
header("Content-type: image/jpeg");
imagejpeg($target_layer);
?>

Step 3)

Now visit your form; it will display the captcha code in your form.