[Adrian Schneider]

For security?

It's easy to spoof the referrer, so it's not reliable at all. AFAIK not all browsers send the header either (though most do).

If you wanted a wildcard, you could use another function like strpos.

PHP Code:

if (strpos($_SERVER['HTTP_REFERER'], 'http://www.example.com') !== 0) {
    
} 


Translates to, if referer string does NOT start with "http://www.example.com" then...

Anyway, not recommended if this is a preemptive strike for security.