This variable is the GETparameters in request line, e.g. foo=123&bar=blahblah; This variable could be changed.
This variable is the current request URI, without any arguments (see $args for those). This variable will reflect any modifications done so far by internal redirects or the indexmodule. Note this may be different from $request_uri, as $request_uri is what was originally sent by the browser before any such modifications. Does not include the protocol or hostname. Example: /foo/bar.html