This category is for sites related to Extensible Markup Language (XML). XML is a subset of Standard Generalized Markup Language (SGML). The Extensible Markup Language (XML) is the universal format for structured documents and data on the Web. Its goal is to enable generic SGML to be served, received, and processed on the Web in the way that is now possible with HTML. XML has been designed for ease of implementation and for interoperability with both SGML and HTML.