- time: documentation ( source)
- date: documentation ( source)
- strtotime: documentation ( source)
- gmdate: documentation ( source)
<?php
echo ("Expires: ".gmdate("D, d M Y H:i:s", time() + 3600)." GMT");
echo "\n";
$date = strtotime("+7 day");
echo date("l, d-M-Y H:i:s T", $date);