PerfectXML is a great place to get started with using XML or learn about advanced applications and new XML technologies. The free library is probably the most valuable source of information on the site. Over 100 sample chapters from numerous books can be viewed, covering a wide range of XML topics. There are also links to XML editors, conversion tools, and many other software resources. Some are free, others have a free trial version, and others are only available in commercial versions. Tech news articles, certification information, and online quizzes are all available from this site. PerfectXML is constantly updated.