I tried writing a script that would display the contents of a cookie set by another website but it didn't work.
<?php echo 'Website cookie is '.$_COOKIE['locale']; ?>
But I get an undefined index error. Can cookies only be retrieved by the issuing site? I've got the add on Cookie Manager in Firefox opened and each cookie has a site and name. So can a cookie only be viewed if the site requesting it also issued it and (obviously) the right name is given? How is the enforced - are web browsers simply programmed this way or do the cookies have some sort of inbuilt security?