Ajax Restaurant

When and Why We should use Ajax

When first time I learned the term Ajax. I was trying to understand what kind value it will add. Before that I will tell one of my funny experience
I was driving with my friend near to Bangalore. It was 1:30 PM. We were searching some small hotel for lunch. We found a one near to the highway. We went there it was a normal road side Indian hotel. There were few people were eating. We ordered a veg thalli for each. The waiter served us a proper south Indian thalli. It has rice, dal, sambar, rasm, curd etc. i wanted to have extra dal. I asked the waiter "Execuse me can I have some dal please". The guy smiled at me told definitely sir. He took my whole thali inside and brought back the same thali with some dal. It was little strange. I thought why he took the whole thali when I had asked for extra dal, he could get me some dal directly.
So when we design our web pages we can always make choice. To update some portion of the page do we really required to take the whole page away from the user. And the poor user has to wait to get back the page. It is not acceptable when we have such powerful browser which are ready to run java script.
I think bringing only dal is easier rather than serving back the whole meal again :)