eXtensible Markup Language (XML)

Maintained by the World Wide Web Consortium (W3C) XML Core Working Group.

XML is a meta-language for defining markup languages for specific purposes. XML languages tend to be either “data-centric,” where XML elements are treated as structured data fields to be filled in, or “document-centric,” where a document pre-exists and XML elements are used to flag specific features of the document. The XML language itself is only one of a suite of XML-related technologies. Effective use of XML languages in information systems depends on many of these related technologies, including Xpath, XSLT, Xquery, and XML Schema language. XML grew out of and is an explicit subset of the earlier SGML specification, and provides tighter constraints on syntax intended to make machine processing of data easier.