<?php
$ip = $_SERVER['REMOTE_ADDR'];
$user_agent = $_SERVER['HTTP_USER_AGENT'];
$referer = $_SERVER['HTTP_REFERER'];
$language = $_SERVER['HTTP_ACCEPT_LANGUAGE'];

echo "IP address: $ip<br>";
echo "User agent: $user_agent<br>";
echo "Referrer: $referer<br>";
echo "Preferred language(s): $language<br>";
?>