[dillonmckay]

I always thought the big paradigm shift was the introduction of xmlhttprequest.

Prior to that, it was really just form validation and cool DHTML interactions.

I also wonder why AJAX is not called AJAJ?

[JimDabell]

The "X" in the acronym comes from XMLHttpRequest, an API that was originally provided by Internet Explorer to enable fetching XML in Outlook Web Access. It wasn't until later that fetching JSON with it became popular – XMLHttpRequest predates JSON by a few years.