Ajax is neither a floor wax nor a desert topping (nor, indeed, a lemon-scented cleaning product!). It’s a blend of a number of standard technologies already familiar to developers and designers:
Extensible Markup Language (XML), a language designed to define other languages. The XMLHttpRequest object can handle the server response in standard XML format as well as plain text.
Extensible Stylesheet Language and Transformation (XSLT), a templating technology for transforming the display of XML information for a receiving client.
The plethora of new web applications that use Ajax, however, suggests that this group of technologies has morphed into a new web model. “Web 2.0” is next-generation-speak encompassing Ajax, a form of Rich Internet Application (so called because much of the application’s functionality can reside in the client browser). Examples of these applications are Google Maps, Gmail, a collaboration suite called Zimbra, an interesting personal search-engine tool called Rollyo (http://www.rollyo.com), and one of the first interactive web maps, this one of Switzerland (see http://map.search.ch/index.en.html). The number of Ajax applications is growing very rapidly. You can find a short list on Wikipedia, at http://en.wikipedia.org/wiki/List_of_websites_using_Ajax.