EXtensible Mark-Up Language (XML) is a versatile language that is found everywhere in today's software. Although HTML predates XML, current versions of HTML (XHTML included) are actually defined using XML document type description (DTD). Knowing XML syntax is an important part of developing usable applications. Below is a collection of interesting links on the subject matter.

XML References
	W3Schools XML Tutorial & Reference
	This is an excellent site for beginners and veterans alike. It contains information on the XML from version 1.0 on and links to the standards definition.
	Microsoft's (MSDN) XML Fundamentals
	Another good place to look for beginner help, or to refresh your memory.
	O'Reilly's XML.com Site
	Every link you ever wanted to follow on the topic of XML. Although we find the site poorly designed, it is worth a visit just for the sheer completeness of their link collection and the breadth of articles offered. For a better list of links, check out their "Resource Guide".