Ajax is a way of developing Web applications that combines:

* XHTML and CSS standards based presentation
* Interaction with the page through the DOM
* Data interchange with XML and XSLT
* Asynchronous data retrieval with XMLHttpRequest
* JavaScript to tie it all together

In the traditional Web application, the interaction between the customer and the server goes like this:

1. Customer accesses Web application
2. Server processes request and sends data to the browser while the customer waits
3. Customer clicks on a link or interacts with the application
4. Server processes request and sends data back to the browser while the customer waits
5. etc....

There is a lot of customer waiting.