As wikipedia tells us, copied from more reliable sources
NOTE - it says right there techniques, not technology. Which you have trouble seeing the difference between. A technology change in tennis is the new composite material for making tennis racquets, while a technique is a different style of hitting the ball with your backhand; maybe that will help you understand the two.
AJAX does NOT provide a NEW ability to communicate with the servers, that has been there with a lot of the available scripting programs for some time, what it does do is allow you to create a page so that interaction can be done without letting the person using the page know it's happening - thus AJAX is loved by spyware and malware people.
Anyway, this technique may well be on the way out as it's not fully compatible with HTML 5 in the way it's currently used.
Also AJAX is NOT as pervasive as you think it is either. It's NOT that common once you get away from the people trying to flood web pages with ads.
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