http://www.bloomington.in.us/~mongin/xml-tutorial/index.htm Dated material (last revised in 2000), but still helpful for basic information on XML.

http://www.xml.com/ A very comprehensive, authoritative, up-to-date source for all things XML (O’Reilly).

http://xml.apache.org/ The Apache XML Project. Open source XML site with wide ranging information on developing standards.

http://webreference.com/xml/reference/standards.html/ Good quick reference for various XML standards and acronyms.

http://www.service-architecture.com/xml/articles/ Good reference site for various industry-specific XML vocabularies.

http://www.xmlfiles.com/xml/ Helpful, simple tutorials on XML topics; good place to learn XML.

http://www.w3.org/ The primary source for all things web related.

http://xml.silmaril.ie/ Another helpful site for answering basic XML questions.

http://www.oasis-open.org/home/index.php Standards body for DocBook and other XML-related activities; very technical but important.

http://www.xml.org/ Covers industry-specific content on XML standards, hosted by OASIS.

http://www.xml.gov/ Covers XML use in government.

http://www.softwareag.com/xml/about/glossary.htm General reference site on XML; extensive glossary, article, expert opinions.

http://www.xmlhack.com/ Good news site for XML developers.

http://www.devx.com/xml Another good site for XML application developers.

http://www.xmlfiles.com/ Good articles for XML developers.

http://www-130.ibm.com/developerworks/xml/ Loads of information on XML, helpful to newbies up to experienced programmers.

http://www.docbook.org/ Official site for DocBook, including full documentation.

http://msdn.microsoft.com/xml/default.aspx Information on XML in the world of Microsoft.

http://www.useit.com/ Jakob Nielsen is an author and known expert and resource on user interfaces, especially Web design strategy and Web usability