AJAX, recommended by google on 2005, seems not bringing in any new technology, but it can exchange data without reload the server page, this really give a more efficient response to user request. This is the innovation. Not only AJAX, but also nearly the whole web 2.0 is based on the old tech. It changed the way to face the internet, It's not "we use computer as a tool", it became to "we r teaching the machine".  <<a fantasitic clip about web 2.0 in youtube >>

 

In the normal life, we don't need to think how to invent a fantastic thing, what we should do is just using different ways to think about the ordinaire things, Maybe sometimes you can also have amazing discovery.