The MIME type text/xml is used to denote the presence of XML documents. The category for this MIME type is "text".

XML stands for Extensible Markup Language and XML documents carry the acronym itself as their extension almost always. It is a markup language much like HTML (Hyper Text Markup Language) and was developed to encode documents for the Internet. XML is defined in the XML 1.0 specifications document released by W3C. It is a free and open standard specification as opposed to proprietary.

XML was designed for usability, generality and simplicity on the Internet. XML is a textual data format that has good support for the languages of the world via Unicode. Even though it was intended to be used with documents, it finds myriad uses in the representations of many things like abstract data structures in web services.

Software developers may use a variety of programming interfaces to access XML data and also several schema systems to help define the XML-based languages.

At the time of writing, there are many hundreds of languages that have been developed that are XML based. Examples of such popular implementations are RSS, ATOM, SOAP, XHTML, etc. It has also become a default for office documents created by the likes of Microsoft Office, OpenOffice.org, etc.