Wikipedia definition

 “AJAX, shorthand for Asynchronous JavaScript and XML, is a web development technique for creating interactive web applications. The intent is to make web pages feel more responsive by exchanging small amounts of data with the server behind the scenes, so that the entire web page does not have to be reloaded each time the user makes a change. This is meant to increase the web page's interactivity, speed, and usability.”

AJAX Facts

AJAX is a set of technologies that give web applications the look-and-feel of desktop applications.

AJAX enables much higher level of performance and ease of use by greatly reducing the number of annoying web page refreshes.

AJAX technologies are not new, AZUR Group has been using AJAX since 1999 to build interactive Web applications with great successes.

Since AJAX is not new, this guarantees web application stability, robustness and security.

What is new about AJAX is that a great number of IT experts are now convinced that it can really help to build richer and faster web applications.