XML, the extensible markup Language, is a universal syntax 
for describing and structuring data independent from the 
application logic.
--> XML isa markup language much like HTML
--> XML was designed to describe data
--> XML tags are not predefined.you must define ur own tags
--> XML is self-describing

XML(Extensible Markup Langauge)is all about describing 
data.An XML tag is not something predefined but it is 
something you have to define according  to your needs.Below 
is a XML which describes invoice data.
<?XML version="1.0" encoding="ISO-8859-1"?>
<student>
<studentnumber>111</studentnumber>
<studentname>SaranKumarReddy.C</studentname>
<totalmarks>790</totalmarks>
<average>79</average>
</student>

For instance in the above example of student all tags are 
defined according to student needs.The XML document is self 
explanatory,any one can easily understand looking at the 
XML data what exactly it means.

In the above example <student></student> tag is the root 
element.Root element is the top most elements for a XML.

XML is case sensitive.
Eg: <student> tag is not same as <Student> tag.