$HTTP_SERVER_VARS

Basic surfer information variables (from HTTP_SERVER_VARS)

[ip] = $HTTP_SERVER_VARS["REMOTE_ADDR"];

// $surfer_info[real_ip] will only contain something if the surfer used a transparent proxy

$surfer_info[real_ip] = $HTTP_SERVER_VARS["X_FORWARDED_FOR"];

$surfer_info[port] = $HTTP_SERVER_VARS["REMOTE_PORT"];

$surfer_info[browser_lang] = $HTTP_SERVER_VARS["HTTP_ACCEPT_LANGUAGE"];

$surfer_info[user_agent] = $HTTP_SERVER_VARS["HTTP_USER_AGENT"];

$surfer_info[request_path] = $HTTP_SERVER_VARS["PATH_INFO"];

$surfer_info[request_query] = $HTTP_SERVER_VARS["QUERY_STRING"];

$surfer_info[request_method] = $HTTP_SERVER_VARS["REQUEST_METHOD"];

$surfer_info[http_referrer] = $HTTP_SERVER_VARS["HTTP_REFERER"];

?>

It is just a row of variables, - it is up to you to decide how they are useful to your script and how to integrate them.
But if you want to see something happening any way, add
print_r($surfer_info);
to the bottom of the script (but before the closing ?>). Doing so will cause the script to show you what information the variables picked up