Ajax, which consists of HTML, JavaScript™ technology, DHTML, and DOM, is an outstanding approach that helps you transform clunky Web interfaces into interactive Ajax applications. The author, an Ajax expert, demonstrates how these technologies work together -- from an overview to a detailed look -- to make extremely efficient Web development an easy reality. He also unveils the central concepts of Ajax, including the XMLHttpRequest object.

In this article, you'll begin with the most fundamental and basic of all Ajax-related objects and programming approaches: The XMLHttpRequest object. This object is really the only common thread across all Ajax applications and -- as you might expect -- you will want to understand it thoroughly to take your programming to the limits of what's possible. In fact, you'll find out that sometimes, to use XMLHttpRequest properly, you explicitly won't use XMLHttpRequest. What in the world is that all about?