[NEWBIE] Confused about usage of $_SERVER['DOCUMENT_ROOT']

PHP General, The Situation: I would like to be able to specify locations of scripts and files relative to the "root" directory from which my web site is served. I thought this was what $_SERVER['DOCUMENT_ROOT'] was for. The Problem: When I use $_SERVER['DOCUMENT_ROOT'], it creates a path starting from somewhere deep down in the server's file structure, below where I even have authorized access. So if I specify a file like so: $imageFile = $_SERVER['DOCUMENT_ROOT'] . "/images/image.jpg"; ... PHP gets lost and doesn't locate it. What I am looking for is a variable which will specify the base directory that my web site is rooted in. In other words, starting from the same directory that my index.html file is in. The Question: How do I specify the directory that my web site is situated in, the same directory where my main index.html file is? Is there a different variable I should be using, or perhaps some configuration of $_SERVER['DOCUMENT_ROOT'] that needs to be applied? What I've Tried So Far: First I went to the on line PHP manual, which is where I found out about $_SERVER['DOCUMENT_ROOT'] in the first place. Of all the server variables available, 'DOCUMENT_ROOT' seems to describe what I'm looking for, but doesn't behave how I would expect. A Google search was equally ineffective in educating me in what basic concept I am missing. Any advice would be much appreciated. -- Dave Gutteridge dave@tokyocomedy.com