What is XML?

XML (eXtensible Markup Language) is a markup language designed to store and transport data. It is both human-readable and machine-readable. Unlike HTML, which is used to display data, XML is used to describe and structure data.

Key Features of XML

1. Self-descriptive structure:

   • Tags describe the data.

   • Example:

     <person>  <name>John</name>  <age>30</age></person>

2. Custom tags:

   • You can define your own tags based on the structure of the data you're working with.

3. Hierarchical (tree) structure:

   • Data is organized in a nested, parent-child structure.

4. Platform-independent and language-independent:

   • Can be used across different systems and programming environments.

5. Supports Unicode:

   • Useful for internationalization (handling of different languages and scripts).

Basic Syntax Rules

• Every tag must be closed:

  <tag>content</tag>

• Tags are case-sensitive:

  • <Name> and <name> are different.

• Elements must be properly nested:

  <a><b></b></a> <!-- correct --><a><b></a></b> <!-- incorrect -->

• The document must have a single root element:

  <root>  <child1></child1>  <child2></child2></root>

XML Declaration (Optional but Recommended)

Placed at the top of the document:

<?xml version="1.0" encoding="UTF-8"?>

Example XML Document

<?xml version="1.0" encoding="UTF-8"?><bookstore>  <book>    <title>Learn XML</title>    <author>Jane Doe</author>    <price>29.99</price>  </book>  <book>    <title>Mastering XML</title>    <author>John Smith</author>    <price>39.99</price>  </book></bookstore>

Common Uses of XML

• Configuration files (e.g., .xml in Java apps)

• Web services (SOAP)

• Data interchange (between systems and applications)

• RSS feeds

• Office document formats (e.g., DOCX, XLSX are ZIP files containing XML)

Related Technologies

• XSLT: For transforming XML documents

• XPath: For querying XML data

• XML Schema (XSD): For defining the structure and data types in an XML document

• DTD (Document Type Definition): An older schema definition system

Would you like to see how to read XML using a programming language (like PHP, JavaScript, or Python)?