Fundamentally, AJAX represents a generic application model that would enable more interactive, more responsive, and smarter Web applications.
The Web was originally designed for browsing HTML documents. As a result, the classic Web application model adopts a "click, wait, and refresh" user interaction paradigm and a synchronous request/response communication mechanism:
However, these two fundamental behaviors of the classic Web model do not work well for software applications. In the context of software applications, the classic Web application model creates many problems: slow performance due to "click, wait, and refresh;" loss of operation context during page refresh; excessive server load and bandwidth consumption due to redundant page refreshes; and lack of two-way, real-time communication capability for server initiated updates.
In the context of software applications, "click, wait, and refresh" and "synchronous request/response" result in slow, unreliable, low productivity and inefficient Web applications. These two basic behaviors must be altered to produce higher performance, more interactive, more efficient Web applications—precisely what the AJAX application model does. In the AJAX model:
In summary, AJAX is not specific to a particular programming language, data exchange format, or network communications object. It is a Web application model that employs partial screen update and asynchronous communication.