How can one troubleshoot issues with PHP files not displaying properly when included in a webpage?

To troubleshoot PHP files not displaying properly when included in a webpage, you should check for syntax errors in the PHP file, ensure that the file is saved with a .php extension, and verify that the PHP code is properly embedded within <?php ?> tags. Additionally, make sure that the server has PHP installed and enabled.

<?php
include 'file.php';
?>