XML--- extensible markup Language --- is an exciting development in web technology. It is the youngest and most comprehensive of markup Language. (Markup refers to any thing on a document that adds special meaning to a particular text; for example, bold text is a form of markup). This language got the name Extensible Markup Language from the characteristic that is not restricted to fixed set of tags, as is HTML (Hypertext Markup Language). An XML user creates his own tags according to need. A tag is a sequence of characters in a markup language used to provide information, such as formatting specifications, about a document.