How can PHP scripts recognize the page they are embedded in without using the URL parameters?

PHP scripts can recognize the page they are embedded in by utilizing server variables like $_SERVER['HTTP_REFERER'] which contains the URL of the page that referred the current request. This information can help the script identify the page it is embedded in without relying on URL parameters.

$referrer = isset($_SERVER['HTTP_REFERER']) ? $_SERVER['HTTP_REFERER'] : 'Unknown';
echo "The script is embedded in the page: $referrer";