What is XML?

XML (eXtensible Markup Language) is a markup language designed to store and transport data in a structured, readable format. It's both human-readable and machine-readable, making it ideal for data exchange between different systems.

What Does XML Stand For?

XML stands for eXtensible Markup Language. The "extensible" part means you can create your own custom tags and structure.

How XML Works

XML uses tags (similar to HTML) to define the structure of data. Each piece of data is wrapped in opening and closing tags, creating a hierarchical structure.

XML Structure

Elements: The basic building blocks defined by tags

Attributes: Additional information stored within tags

Nesting: Elements can contain other elements

Root Element: The top-level element that contains all others

XML vs Other Formats

vs JSON: XML is more verbose but supports attributes and namespaces

vs HTML: XML is for data, HTML is for presentation

vs CSV: XML supports hierarchical data structures

Common Use Cases

Configuration Files: Application and system configuration

Data Exchange: Sharing data between different systems

Web Services: SOAP APIs and other web service protocols

Document Storage: Storing structured documents

RSS Feeds: Syndicating content across the web

XML Syntax Rules

All tags must be properly closed

Tags are case-sensitive

Elements must be properly nested

One root element per document

Attribute values must be quoted

Example XML Structure

xmlCODE

<?xml version="1.0" encoding="UTF-8"?>
<bookstore>
  <book category="fiction">
    <title>Harry Potter</title>
    <author>J.K. Rowling</author>
    <year>1997</year>
  </book>
  <book category="non-fiction">
    <title>Learning XML</title>
    <author>John Doe</author>
    <year>2020</year>
  </book>
</bookstore>

XML Technologies

XPath: Query language for XML documents

XSLT: Transformation language for XML

XML Schema: Define structure and validation rules

DOM: Programmatic access to XML documents

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*XML remains a fundamental technology for data exchange and configuration. Understanding XML helps you work with many enterprise systems and APIs!*