Referer Question

Hi, Say I have an image called in a page which is actually a PHP script (A banner image for example). Is there any variable I could use to detect where the the one that entered the page and ran the php script came from? I guess it's something like the referer of HTTP_referer or something. I could do it using some javascript and pass it to the php but that's not really acceptable. Thanks in advance, George E. Papadakis Project Manager Phaistos Networks S.A - http://www.phaistosnetworks.gr georgep@phaistosnetworks.gr T: +30 892 24450 F: +30 892 23206 - A DOL Digital Company