XML
XML (Extensible Markup Language) is a markup language that defines a set of rules for encoding documents in a format that is both human-readable and machine-readable. It is widely used for representing structured data, such as configuration files, web services (SOAP), and document formats, by allowing users to define their own custom tags and document structure.
Developers should learn XML when working with data interchange, configuration management, or legacy systems, as it provides a standardized way to structure and share data across different platforms and applications. It is essential for scenarios like web services (e.g., SOAP APIs), document storage (e.g., Microsoft Office files), and configuration files in various software frameworks.