Here is a list of some famous web applications that make use of AJAX.
A user can drag an entire map by using the mouse, rather than clicking on a button.
As you type, Google will offer suggestions. Use the arrow keys to navigate the results.
Gmail is a webmail, built on the idea that email can be more intuitive, efficient and useful.
Now it's even easier and more fun to get where you're going!
Try these two examples one by one and you will feel the difference. While trying AJAX example, there is not discontinuity and you get the response very quickly, but when you try the standard GCI example, you would have to wait for the response and your page also gets refreshed.