An Acronym for Asynchronous JavaScript And XML.

Refers to the idea of using JavaScript to cause actions on the the WebServer or inject new data from the server into a HTML page without forcing reloads in the WebBrowser, in order to achieve more responsive web applications that lessen the gap to desktop applications. Usually also implies the use of XMLHttpRequest? objects, first introduced in IE, although the same technique has been possible long before that using hidden frames (cf. Google Maps). The "XML" part is also a bit of a misnomer, as it is getting ever more popular to push data around in JSON format instead.

Many people scoff that the "AJAX" term has no particular technical definition and really is just a rebranding of "DHTML". Others argue that the merit of the "AJAX" term is not technical, but social, in that it captures and conveys the new awareness of DHTML as a tool for purposes not previously conceived of.