XML (eXtensible Markup Language) is a text-based format used to store and transport structured data. Unlike HTML, which focuses on displaying information, XML is designed to describe and organize data in a readable and flexible way. It allows developers to define their own tags, making it suitable for many different types of applications and data exchange systems.

Example: Simple XML document

<message>
    <sender>Alice</sender>
    <receiver>Bob</receiver>
    <text>Hello!</text>
</message>

This example represents a structured message with clearly defined data elements.