Why people prefer XML
XML stands for Extensible Markup Language and that was design to transfer and store data. But we can display data in XML by using style sheets (CSS, XSLT). Not like in HTML the tags are not predefined in XML and you must define your own tags as you wish.
A good programming practice is naming tags related to the information it carries, so another developer can easily identify tags.
Another huge advantage is easy to work with data bases and computer systems. In other cases they sore data in data bases as incompatible types. But XML stores data in text format and it makes easy when storing because format is independent by software and hardware variations. The data in Xml files are send using XML DOM (Document Object Model) objects.
Try to learn XML. It will reduce your stuff.
This is a great tuutorial for beginers. http://www.w3schools.com/xml/xml_whatis.asp