Extensible Markup Language (XML) is a simple, very flexible text format
derived from SGML (ISO 8879). Originally designed to meet the challenges
of large-scale electronic publishing, XML is also playing an increasingly
important role in the exchange of a wide variety of data on the Web and
elsewhere.
XML stands for EXtensible Markup Language
XML is a markup language much like HTML XML was designed
to describe data
XML tags are not predefined. You must define your own
tags
XML uses a Document Type Definition (DTD) or an XML
Schema to describe the data
XML with a DTD or XML Schema is designed to be self-descriptive