Ajax (Asynchronous JavaScript and XML)
Asynchronous JavaScript and XML, I can explain this with just one picture.
This picture show us that the browser doen’t connect to a websever to get html pages any more. for example, if you open gmail.com, then you will get bunch of xml document instead of html.
with those xml document, the JavaScript will generate proper html pages.
it’s pretty simple concept, huh?
Wikipedia says
Simple tutorial
Ajax blog
Java BluePrints Solutions Catalog
Technical article