.xml File — Extensible Markup Language

XML (Extensible Markup Language) is a markup language and data format standardized by the W3C in 1998, designed for both human and machine readability. XML uses nested elements with opening and closing tags to structure data hierarchically, with attributes for metadata. Unlike HTML which has predefined tags, XML allows users to define their own tag vocabularies for specific domains. XML has been foundational to web technologies including XHTML, SOAP, RSS/Atom feeds, SVG, MathML, and XSLT transformations. The format is validated against schemas (DTD, XSD, RelaxNG) that define allowed structures and data types. XML supports namespaces for combining vocabularies, XPath for querying, and XSLT for transformation. While JSON has largely replaced XML for web APIs due to its lighter syntax, XML remains dominant in enterprise integration (SOAP, ESB), document formats (OOXML, ODF, EPUB), publishing (DocBook, DITA), government data exchange, and configuration for Java/Android applications. XML's verbose syntax provides self-describing data with strong typing and validation capabilities that JSON lacks. The format's maturity and extensive tooling make it irreplaceable in many enterprise and standards-based contexts.