XML

XML (Extensible Markup Language) is a markup language similar to HTML, but without predefined tags to use.

PHP offers several set of functions to handle XML : domxml, simplexml, xmlreader, xmlwriter.

<?php
$string = <<<XML
<?xml version='1.0'?>
<document>
    <cmd>login</cmd>
    <login>Richard</login>
</document>
XML;

$xml = simplexml_load_string($string);
print_r($xml);

?>

Documentation

See also PHP XML Tutorial: Create, Parse, Read with Example

Related : SimpleXML, DOM, XMLwriter, XMLReader