Feature of Extensible Markup Language :-
1> XML is heavily used as a format for document storage and processing, both online and offline.
2> Content-based XML markup enhances searchability, making it possible for agents and search engines to categorize data instead of wasting processing power on context-based full-text searches.
3> The XML document which uses the DTD has the XML tags in it. It is in the XML document, the tags or the elements are defined for the data.
4> XML does not allow References to external data entities. Named character references are not allowed in XML. XML does not allow empty comment declaration.
5> XML is extensible, because it only specifies the structural rules of tags. No specification on tags them self.