If you develop software based in PHP but you don't know to show its extension(.php) like http://foo.com/auth instead of http://foo.com/auth.php, you can make your PHP page work without its extension by adding ForceType application/x-httpd-php on .htaccess
What you should do is super simple. Just add below text to .htaccess or php.ini having that PHP code.
.htaccess
ForceType application/x-httpd-php