Ajax
"Ajax, for Asynchronous JavaScript + XML. Weaving together existing technologies, Ajax will help make Web services feel more like programs that run on the user's own computer, releasing Internet content from the limitations of conventional Web design by reimagining the browser as an operating system." (http://www.popularmechanics.com/specials/features/2076876.html?page=4&c=y)
Definition
From the Wikipedia article at
"Ajax, shorthand for Asynchronous JavaScript and XML, is a web development technique for creating interactive web applications. The intent is to make web pages feel more responsive by exchanging small amounts of data with the server behind the scenes, so that the entire web page does not have to be reloaded each time the user requests a change. This is meant to increase the web page's interactivity, speed, and usability." (http://en.wikipedia.org/wiki/AJAX)
Discussion: why Ajax is so important
Yihong-Ding:
"AJAX solves the problem of asynchronously processing varied resources in one Web page. In short, AJAX eliminates the processing overhead of enforced synchronizing of multiple resources in the same page. Because of AJAX, the Web has been decomposed from pages as resource units to portions of pages as resource units. Informally, we may also say that AJAX makes the Web evolve from a web of URLs to a web of URIs. Such an evolution makes the Web be very different from before.
Although GMail is not the first AJAX application, it is the first influential AJAX application at the global scale that demonstrates the power of AJAX. By the success of GMail, AJAX caught the mainstream attention. With the wide adoption of AJAX, the rise of Web 2.0 became unstoppable.
GMail is a phenomenal product. The use of AJAX makes GMail be an interactive platform. Unlike the traditional email services such as Hotmail or Yahoo Mail (the versions before GMail), GMail let users feel that they are performing a regular desktop functions since the page refreshing issue has been nearly eliminated. Therefore, the first time in history two email users feel that they are using a shared desktop and interactively messaging each other. GMail becomes a platform for emails users more than simple an email service. This fundamental upgrade to the intent of email makes GMail immediately be popular among the Web users, let it alone the significant larger storage spaces GMail promised for its users." (http://yihongs-research.blogspot.com/2008/08/age-of-google-3-web-20.html)