Ashish has covered most of the important points. It is very important to understand what XML is not. It is not a language, it is not an application, it has no significance on its own existence as an individual entity. You can only make sense out of the XML data when you parse it and integrate the results with your application. Think of it as HTML. You can make sense out of it( unless you are ready to hurt your eyes reading between the lines in the raw HTML file ) only when you open it in the browser.
Stanley,
Since XML represents data, using XSL( eXtensible Stylesheet Language ), you can generate human-readable files in popular formats( HTML, text etc. ) XSLT( XSL Transformation ) is a process that converts an XML document into other readable format by applying the stylesheet you supply.
ie., XML + XSL -----> run it through XSLT ---> gerates human-readable XML( like HTML/text etc ).
Hope that helps!
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Ajith Kallambella M. Sun Certified Programmer for the Java�2 Platform.
IBM Certified Developer - XML and Related Technologies, V1.