• The XML specification.
• The Namespaces in XML specification.
• The Extensible Style Language (XSL) W3C note.
• The Cascading Style Sheet (CSS) W3C note.
• The XML Linking Language(XLink)
• The XML Pointer Language
• The Document Object Model specification.
• A mailing list for XML developers 討論區

Microsoft :

• Microsoft's XML site
• Microsoft's XSLT Developer's Guide

XML FAQs:

• Frequently Asked Questions about the Extensible Markup Language
• 中文 XML FAQ
• 中文 XML 入門 -- 問與答
• FINETUNING COM
• Textuality FAQ on XML

XML WebSite:

• Introducing the Extensible Markup Language (XML).
• IBM Developers: XML : Overview
• 陳長念 活用XML
• XML 台灣資訊網
• XML 中文網站
• he WDVL: Introduction to XML For Web Developers.
• XML com
• XML Tutorial: Learning XML

• XML links and resources
• XML Links, by Adam Rifkin and Rohit Khare
• Symon's Extensible Markup Language (XML) Page
• xmlhack