What is the significance of using $_SERVER['DOCUMENT_ROOT'] in PHP when including files across different virtual hosts?

When including files across different virtual hosts in PHP, using $_SERVER['DOCUMENT_ROOT'] is significant because it provides the absolute path to the root directory of the current virtual host. This ensures that the included files are correctly located regardless of the virtual host being accessed.

<?php
include $_SERVER['DOCUMENT_ROOT'] . '/path/to/your/file.php';
?>