This section provides the most basic concepts of XML to work with ZK. If you are familiar with XML, you could skip this section. If you want to learn more, there are a lot of resources on Internet, such as http://www.w3schools.com/xml/xml_whatis.asp and http://www.xml.com/pub/a/98/10/guide0.html.

XML is a markup language much like HTML but with stricter and cleaner syntax. It has several characteristics worth to notice.