PHP/HTML/HTTP REFERER

HTTP_REFERER and HTTP_USER_AGENT

   <source lang="html4strict">

<?php

           if (isset($_SERVER["HTTP_REFERER"])) {
                   print "The page you were on previously was {$_SERVER["HTTP_REFERER"]}
";
           } else {
                   print "You didn"t click any links to get here
";
           }
   ?>
   <a href="refer.php">Click me!</a>
 
 </source>