XML finds several applications in business and, increasingly, in everyday life. It provides a common
data format for companies that want to exchange documents using Web services. This chapter is about
XML as a language and its related technologies. The XML technologies that I will specifically introduce
in this chapter are: XML document elements, namespaces, entities, DTD, XDR, XSD, XSD schema data
types, XSLT, XML DOM, XPath, SAX, XLink, XPointer, and XQuery.
you can learn xml at here