• Ajax: A New Approach to Web Applications, by Jesse James Garrett. The original article which coined the term.
• Why Ajax Matters Now by Jesse James Garrett.
• Ajax gives software a fresh look Blurring the line between desktop and Web applications.
• Weighing the Alternatives How Ajax stacks up against competing RIA approaches.
• JavaScript refactoring for safer, faster, better Ajax.
• Sessioning with XMLHttpRequest Using HTML and JavaScript to connect the presentation layer directly to XML data.

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Tutorials

• AJAX:Getting Started by Mozilla Developer Center.
• Dynamic HTML and XML: The XMLHTTPRequest Object by Apple.
• Cross-browser Ajax Tutorial using the Sarissa library.
• ASP.NET Spiced: AJAX from MSDN.
• Ajax Programming in BEA WebLogic Portal by O’Reilly Media.
• Mastering Ajax, Part 1: Introduction to Ajax.
• Mastering Ajax, Part 2: Make asynchronous requests with JavaScript and Ajax.
• Mastering Ajax, Part 3: Advanced requests and responses in Ajax.