What is XML

XML stands for Extensible Markup Language. It is a versatile markup language designed to store, transport, and exchange structured data in a format that is both human-readable and machine-readable. XML was first introduced as a W3C (World Wide Web Consortium) recommendation in 1998 and has since become a widely used standard for data representation and interchange.

Key Features of XML:

1. Hierarchical Structure: XML documents are organized as hierarchical trees, where each element can have child elements, and elements at the same level are considered siblings.
2. Tags and Elements: XML uses start and end tags to mark the beginning and end of elements. Elements are used to represent data objects, and they can contain attributes, nested elements, or text content.
3. Attributes: Elements can have attributes, which provide additional information about the element’s data.
4. Self-Descriptive: XML documents are self-descriptive, meaning that they include the necessary information to describe the data they contain. XML documents often start with a declaration that specifies the XML version and encoding.
5. Extensibility: The “Extensible” in XML refers to its flexibility in allowing users to define their own custom elements and attributes, tailoring the structure to specific data requirements.
6. Platform-Independent: XML is a platform-independent format, making it suitable for data exchange between different systems and programming languages.
7. Human-Readable and Machine-Readable: XML is both human-readable and machine-readable. Its plain text format allows developers to understand the structure and content easily, and XML parsers can efficiently process it.
8. Unicode Support: XML supports Unicode characters, allowing it to represent text in various languages and character sets.

Example of a Simple XML Document:

<bookstore>
  <book>
    <title>XQuery 101</title>
    <author>John Doe</author>
    <price>25.00</price>
  </book>
  <book>
    <title>XML Fundamentals</title>
    <author>Jane Smith</author>
    <price>30.00</price>
  </book>
</bookstore>

In this example, we have an XML document representing a simple bookstore. It contains two “book” elements, each with “title,” “author,” and “price” elements.

XML is widely used in various domains and applications, such as web services, data exchange, configuration files, document storage, and many other scenarios where structured data needs to be represented and shared in a standardized format. XML is a foundational technology for the Semantic Web and plays a critical role in data integration and interoperability.