XML

XML (eXtensible Markup Language) is a markup language designed to store, structure and transport data in a human-readable and machine-processable format. Unlike HTML, which defines how data is displayed, XML defines what the data is. It is used to represent hierarchical data through a system of nested elements marked by opening and closing tags.

XML is both platform-independent and language-independent, making it ideal for enabling data interchange between heterogeneous systems. It supports metadata through attributes and can be validated using schemas (such as XSD) to ensure data integrity and consistency. XML documents follow a strict tree structure, where each node can contain child elements, attributes, and text content.

XML is widely used in:

• Web services and APIs (especially SOAP-based)
• Data exchange between enterprise systems (e.g. ERP, PLM)
• Configuration files in software applications
• 3D visualisation pipelines, for example to describe scene graphs or CAD metadata
• Industry-specific formats like BIM/IFC, GML (Geography Markup Language) and COLLADA

Although XML has in many cases been replaced by more lightweight alternatives like JSON, its strong schema support and ability to handle complex, nested data structures still make it a reliable choice for industrial and scientific applications.

See also: JSON