Extensible Markup Language (XML)


XML London Conference

Balisage Markup Conference

  1. Introduction
  2. Working Groups
  3. Events
  4. Other Resources
  5. Contact

Nearby: XML Specifications and Translations of them.


Extensible Markup Language (XML) is a simple, very flexible text format derived from SGML (ISO 8879). Originally designed to meet the challenges of large-scale electronic publishing, XML is also playing an increasingly important role in the exchange of a wide variety of data on the Web and elsewhere.

This page describes the work being done at W3C within the XML Activity, and how it is structured. Work at W3C takes place in Working Groups. The Working Groups within the XML Activity are listed below, together with links to their individual web pages.

You can find and download formal technical specifications here, because we publish them. This is not a place to find tutorials, products, courses, books or other XML-related information. There are some links below that may help you find such resources.

You will find links to W3C Recommendations, Proposed Recommendations, Working Drafts, conformance test suites and other documents on the pages for each Working Group. Each document also contains email addresses you can use to send comments or questions, for example if you have been writing software to implement them and have found problems or errors.

Please do not send us email asking us to help you learn a language or specification; there are plenty of resources online, and the people editing and developing the specifications are very busy. We are interested in technical comments and errata.

If your organization would like to join the W3C, or if you would like to participate formally in a working group (and have the necessary resources to attend meetings), you can read more about the Consortium.

Working Groups

There is more detail about each of these Working Groups in the Activity Statement and also on the individual Working Group public web pages.

Most Working Groups have both a public web page and another more private one that is only accessible to W3C Members. The private page has telephone numbers, schedules for meetings and conference calls, links to internal editing drafts, and other administrative information.

XSLT Working Group

The XSLT Working Group is responsible for XSL Transformations (XSLT) and a number of supporting specifications.

You can read the XSLT Working Group Public Page and they also have a member-only page.

The Efficient XML Interchange Working Group

The Efficient XML Interchange Working Group is responsible for developing ways to exchange XML documents in ways that are as efficient as is practical without compromising the interoperability of XML itself. This Working Group is not about producing a closed, proprietary or obfuscated “binary XML ”—The W3C is all about increasing interoperability! The EXI format is a compressed stream of parse events that can use an XML Schema to avoid having to transmit known information and to use native type representations. The receiver of an EXI stream doesn't have to reconstitute the original document, but can process the parse events directly as if parsing had happened, saving CPU, memory, time and bandwidth.

You can read the Efficient XML Interchange Working Group Public Page; there is also a member-only page.

XML Query Working Group

The XML Query Working Group is working on the XML Query Language, a way to provide flexible query facilities and processing of forests of trees, typically exchanged using XML or JSON. This includes publication of XQuery and also XPath, in conjunction with the XSLT Working Group.

You can read the XML Query Working Group Public Page and there is also a member-only page.

Some XML-related events

XML Prague, the leading XML-specific conference in Europe.

markupforum, in Stuttgart is a symposium that has a local emphasis on publishing.

Balisage Markup Conference

Balisage is the leading conference relating to the theory and practice of XML and other markup and has moved from Montreal to Washington DC.

XML London Conference

XML London is in June at University College, London, UK.

XML Amsterdam

XML Amsterdam is a sister event to XML Prague in the Spring.

Other Resources

There are so many resources related to XML that we can't possibly list them all here. This is a good thing, because it means XML is a success! In addition to a history of the development of XML at W3C, there is an extensive index at the Cover Pages, maintained by Robin Cover. The individual Working Group public web pages may have links to specific resources. There are Usenet newsgroups (e.g. comp.text.xml) and public mailing lists (e.g. xml-dev).

You could also try a search engine such as Google for:


Liam Quin, XML Activity Lead



The XML specification, and other information specific to the XML Core Working Group, has moved to the XML Core Working Group Public Page.

There is also a separate page for Translations.


There is a separate page documenting the xml-spec DTD used for many of our specifications.

There is also a Google+ page for XML.