On PHPMaster.com today there's a new tutorial introducing you to SimpleXML, a handy bit of functionality included with the base PHP install to make working with XML (well, reading it) much simpler.
Parsing XML essentially means navigating through an XML document and returning the relevant data. An increasing number of web services return data in JSON format, but a large number still return XML, so you need to master parsing XML if you really want to consume the full breadth of APIs available. Using PHP's SimpleXML extension that was introduced back in PHP 5.0, working with XML is very easy to do. In this article I'll show you how.
He starts with some basic usage of the SimpleXML parsing, giving an example XML to parse, the resulting object and how to access the data inside it. There's also a bit about dealing with namespaces in the XML you're parsing and a more practical example - parsing the output of a YouTube feed to get links to various videos.