if it doesn't end in an extension, eg.
epinions.com/login - its mostly likely written in C/C++ or VB.
If your asking refering to something like this epions.com?action=getpage&category=services&page=index
then you use a page in php or something else and use
<?
if ($action == "getpage") {
?>
some html
<?
}
?>
etc....
