In recent years, the World Wide Web (WWW) has been continuously evolving. Newly coined terms like Web 2.0 and AJAX have established themselves in the world of modern web development and are enthusiastically embraced by interested web developers and users. The increased interest that AJAX currently enjoys is due to visually appealing and highly interactive web applications that resemble desktop applications in their behavior. But what exactly is behind this new buzzword? This book explores that question. It examines in a simple and comprehensible way whether AJAX is truly a novel and revolutionary web technology or if it is rather a product of already existing and well-known technologies that has simply been introduced under a new name. Furthermore, the motives for this are also discussed.