XML (eXtensible Markup Language) is a markup language that defines rules for encoding documents in a format that is both human-readable and machine-readable. Unlike HTML, XML is semantic—it describes the structure of data rather than how to display it.

W3C XML Specifications

• Well-Formedness: All XML documents must be well-formed, meaning they have a single root element, all tags are properly nested, and attribute values are quoted.
• Namespaces: XML namespaces prevent element name conflicts by qualifying element names with a unique prefix bound to a URI.
• Node Structure: XML documents form a tree structure with elements, attributes, text nodes, comments, and processing instructions as nodes.

Formatting Options

• Indent Size: Controls spacing per nesting level (2 spaces, 4 spaces, or tabs).
• Collapse Content: Keeps short text content on the same line as parent tags for compact output.

Use Cases

XML remains critical in enterprise systems, web services (SOAP), configuration files, document formats (Office Open XML), and data interchange between heterogeneous systems.