XML introduction

XML (eXtensible Markup Language) is a W3C (www.w3c.org) recommendation that defines a format used to store, exchange, process or display data or documents.
It comes from SGML and HTML.
It is designed to be both human-readable and easy to automatically process.

XML has been described as "HTML on steroids": a version of HTML that enforces strict markup and that allows custom tags to be defined.

XML is based on descriptive markup: it makes it possible to describe what the data is instead of what it looks like.