XML, or Extensible Markup Language, is a very popular format used to store and share data. In a nutshell, XML stores information in a tree-based text format that allows both you and I as well as computers to easily read the data. I'm sure you have used XML-like languages directly or indirectly, to borrow two popular examples, if you have ever used RSS feeds or have written XHTML pages.
This is a companion discussion topic for the original entry at http://www.kirupa.com/net/readingXML.htm