Advantages and Disadvantages of Ajax

Ajax is a novel method for Web-based application development. It stands for Asynchronous JavaScript and XML. The word is firstly used by Jesse James Garrett in February 2005 [1, 2]. The technique has been widely used by many applications on the Web.
There are advantages and disadvantages for Ajax techniques. One important advantage is that Ajax makes Web pages fancy. It facilitates complex interactions between the application and the users without the need of reloading the entire page [3].
Ajax techniques also have some disadvantages. One disadvantage is that it increases the development time and cost of Web applications. It is reported that Ajax-based applications are hard to build and maintain [4]. Another disadvantage is that Ajax decreases the accessibility of Web applications. Not all browsers support JavaScript and XMLHttpRequest, especially some old browsers, mobile devices and screen readers [5].
As the development of the Ajax techniques, it could be useful to learn it well.

[1] http://en.wikipedia.org/wiki/Ajax_%28programming%29
[2] http://www.adaptivepath.com/publications/essays/archives/000385.php
[3] http://dev2dev.bea.com/pub/a/2005/08/ajax_introduction.html
[4] http://www.interaktonline.com/Support/Articles/Details/AJAX:+Asynchronously...309
[5] http://www.webaim.org/techniques/ajax/