Get Domain & Subdomain from URL

preg_match('/^(?:www\.)?(?:(.+)\.)?(.+\..+)$/i', $_SERVER['HTTP_HOST'], $matches);

define('PROTOCOL', strtolower(substr($_SERVER['SERVER_PROTOCOL'],0,strpos($_SERVER['SERVER_PROTOCOL'],'/'))).'://');
define('SUBDOMAIN', $matches[1]);
define('DOMAIN', $matches[2]);
define('HERE', $_SERVER['REQUEST_URI']);

If you're at http://www.sub.domain.com/page, then: PROTOCOL = http:// SUBDOMAIN = sub DOMAIN = domain.com HERE = /page