Here’s an infographic I made for my QCon talk this week, Single Page Apps and the Future of History:

I think it sums up a key point about Ajax, which is sometimes overlooked: Asynchrony. One of my first posts on Ajax, back in 2005, covered it, but it still took years to really sink in. At the time, I was thinking mostly of “Asynchronous” as XHR’s asynchronous mode, so seeing it in contrast to running XHR synchronously. But really, the big deal about Ajax is the UI can carry on, while networking happens in the background. That’s what makes filling out forms faster and what makes tools like Google Docs possible, especially in multi-user mode.