From W3C Wiki

Extensible Markup Language (XML) is a W3C recommendation for creating special-purpose markup languages. It is a simplified subset of SGML, capable of describing many different kinds of data.

Its primary purpose is to facilitate the sharing of structured text and information across the Internet. Languages based on XML (for example, RDF in RdfXmlSyntax, SMIL, MathML, XSIL and SVG) are themselves described in a formal way, allowing programs to modify and validate documents in these languages without prior knowledge of their form.

XML on Wikipedia

hmm... ProxyTopic... I wonder what purpose this topic serves.

Don't get why this is a proxy topic. Is there a page it comes from? --AndrewCates