XML namespaces provide a simple method for qualifying element and attribute names used in Extensible Markup Language documents by associating them with namespaces identified by URI references. (W3C Recommendation 14 January 1999)

An attempt by James Clark at a less confusing alternative explanation of the mechanism described in the XML Namespaces Recommendation.

XML Namespaces provides a method to avoid element name conflicts. This page gives examples and solutions.

A collection of whitepapers, perspectives and history on XML namespaces, including links, references and contacts.

an HTML-based markup language designed to contain a human-readable description of an XML namespace as well as pointers to multiple resources related to that namespace. Examples of such related resources include schemas, stylesheets, human-readable doc...

Questions and answers about Namespaces in XML as maintained by Ronald Bourret.

This article discusses a number of myths that have arisen around XML namespaces, examining possible sources, clarifying what the recommendation says about them, and pointing out ways to resolve the issues they raise. By Ronald Bourrett.

Questions and answers about Namespaces in XML. By John E. Simpson.

A first look at this W3C Recommendation on Namespaces in XML. By Tim Bray.

The section of the W3C's "Extensible Stylesheet Language (XSL) Version 1.1" specification that defines the XSL namespace.