Here is the XML Easy Definition for Beginners and Students:
The XML is not a language like HTML, but a set of rules for creating new markup languages. It is a meta-markup language. It allows developers to create custom tag sets for special uses. It structures, stores, and transports the information.
The Extensible Markup Language (XML) is a W3C standard for text document markup. It is a text-based markup language that allows you to store data in a fully organized format by using meaningful tags.
The term ‘extensible’ indicates that you can extend your ability to define a document by describing meaningful tags for the application.