AJAX stands for Asynchronous Javascript and XML and was introduced by Google in 2005. It is not a new language but new way to use already existing standards to create rich user experiences online like Google Mail. The main advantage of AJAX is that it lets you reload only certain parts of a website unlike the regular procedure of reloading the entire document even if only one character was changed. This is archived with the XMLHTTPRequest. The progress of a response by server can be accessed with the readystate property. With an if statement the status can be retrieved. The possible responses are: not initialized, request has been set up, has been sent, is in process, and is complete.
Web Applications built with AJAX deliver higher usabilitity and a desktop app like feel.
