What are some common uses of captchas in PHP applications?

Captchas are commonly used in PHP applications to prevent automated bots from submitting forms or accessing certain resources. By implementing a captcha, users are required to complete a challenge (such as typing distorted text or selecting images) to prove they are human. 

// Generate a simple captcha image
session_start();
$random_number = rand(1000, 9999);
$_SESSION['captcha'] = $random_number;

$im = imagecreatetruecolor(100, 38);
$bg_color = imagecolorallocate($im, 255, 255, 255);
$text_color = imagecolorallocate($im, 0, 0, 0);
imagestring($im, 5, 5, 10, $random_number, $text_color);

header('Content-type: image/png');
imagepng($im);
imagedestroy($im);

Keywords

captcha PHP applications security form validation image processing

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