Web-developers can create amazing web-applications with AJAX. Stikkit, Netvibes, GMail and dozens of further web-projects offer a new level of interactivity we’ve used to give up the idea of. Modern web-applications can be designed with enhanced user interfaces and functionalities, which used to be the privelege of professional desktop-applications. AJAX makes it possible to create more interactive, more responsive and more flexible web-solutions. And it’s the first step towards rich internet applications of the future.

Asynchronous JavaScript and XML isn’t a new programming language, as it is often mistakingly called. Basically, AJAX is a set of XHTML, CSS, DOM, XMLHttpRequest and XML, put together and used together for the same purpose – to improve the user-server-interaction.

http://www.smashingmagazine.com/2007/06/20/ajax-javascript-solutions-for-professional-coding/