XML is a markup language for documents containing structured information. It looks like HTML, but it is just for holding data. It has many uses these days and is becoming a big thing fast. It is worth learning. In addition you should pick up XSL which allows you to transform the XML into a viewable web page. Here are links to get youy started


http://www.xml101.com
http://www.xml.com

It may seem a bit confusign at first, but you will find it is actually very simple.