What is XML

                            XML Stands for Extensible markup Language. It was language that has been designed to describe the content, present under text document. So it was known as  describing language and also platform  independent .
                          
                                      Any language that represents data in the form of Tags can be called as Markup Language and any thing that gets enclosed under angular braces is a tag.

                 XML is used for describing content of a t ext document.  so XML was Describing Language. 
                 It was XML Parser. both these were part of a browser. 

                   XML is not, to create an XML document we need to satisfy a set of rules that were prescribed by W3C as following.

• An XML Document has to be saved with .XML extension.
• An XML Document cannot be left empty.
• Data under XML document should be present only under tags, where every tag should have a start and end element.

Eg:   <Tag> 1 </Tag>

           <Tag id ="1" />

Note : Tags can also have attributes which were also user defined  . A value to attribute should be enclosed under double quotes.

• While defining tags start and end tag should match in case.

Eg:        <Abc>Hello </Abc>        // Valid

                 <Abc>Hello </abc>         // Invalid