"Asynchronous communication between the client and the
server forms the backbone of AJAX. Although an asynchronous
request-response method can provide significant value in the
development of rich functionality by itself, the results are lot
more pronounced when used in conjunction with other functional
popularity of AJAX stems from such usage.
"Client-server communication can be achieved either by using
XMLHttpRequest(). Due to certain limitations of IFrames,
XMLHttpRequest has gained a lot more acceptance. While IFrame can
also be an effective option for implementing AJAX-based solutions,
in this article, we will focus largely on an XMLHttpRequest-based
implementation. The primary advantage of using AJAX-based
interfaces is that the update of content occurs without page
refreshes. A typical AJAX implementation using XMLHttpRequest
happens as described in the following steps:"