Responsible Asynchronous Scripting

Asynchronous or remote scripting has been lurking in the background of web app development for quite some time now. Originally dependent on proprietary technology like Java applets, ActiveX and Flash or clever combinations of disparate technologies like images and cookies, native support for the XMLHttpRequest (XHR) object in modern browsers has made it easier than ever to make web apps more responsive and more like their desktop counterparts. This lower barrier to entry also makes it easier to make poor decisions and inappropriate use of a powerful technology.

Inman, Shaun. Vitamin (2008). Articles>Web Design>Server Side Includes>Ajax