what is an XML document
Extensible Markup Language (XML) is a markup language that defines a set of rules for encoding documents in a format which is both human-readable and machine-readable. It is defined by the W3C 's XML 1.0 Specification and by several other related specifications, all of which are free open standards.imple API for XML (SAX) is a lexical, event-driven interface in which a document is read serially and its contents are reported as callbacks to various methods on a handler object of the user's design.