What is XML and How Does it Work?

What is XML?

XML (eXtensible Markup Language) is a language for storing and transporting data in a structured, human-readable format. Unlike HTML, you define your own tags.

An XML Document

<?xml version="1.0" encoding="UTF-8"?>
<bookstore>
  <book category="tech">
    <title>Clean Code</title>
    <author>Robert Martin</author>
    <price>35</price>
  </book>
</bookstore>

Key Rules

• One root element wraps everything.
• All tags must close and nest properly.
• Tags are case-sensitive.
• Attribute values must be quoted.

Where XML is Used

• Config files (Maven pom.xml, Android layouts).
• RSS feeds & sitemaps.
• SOAP web services.
• Office documents (.docx is zipped XML).

FAQs

XML vs HTML?

HTML displays data with fixed tags; XML stores data with custom tags. More in our XML guides.

Is XML still relevant?

Yes for config and enterprise systems, though JSON dominates web APIs now.