HTTP Headers

["Hamid M. Maydanchi" <hamid@xxxxxxxxxxxxxx>]

Dear people,
could you please let me know where can I find some information about HTTP
Header.

I appreciate if you could tell me the meaning of the following header which
is used in php programming.
<?php

header("Expires: Mon, 26 Jul 1997 05:00:00 GMT");

header("Last-Modified: " . gmdate("D, d M Y H:i:s") . "GMT");

header("Cache-Control: no-cache, must-revalidate");

header("Pragma: no-cache");

?>


with best regards,
Hamid Maydanchi
-------------------------------------
Hamid M. Maydanchi
E-mail:  hamid@xxxxxxxxxxxxxx
URL:  http://www.co.umist.ac.uk/~hamid/
Tel No. +44 -(0161)- 272 8292
Mobile:07939 939 529
office: +44-(0161) 200 3388
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