Delivery and Display

I sometimes find myself wondering about how web application data is delivered, and how it is displayed. Well, I actually have a good understanding of the mechanics behind it all — HTTP and HTML are the prominent technologies. What I don't understand is how the thinking behind these two technologies is changing. There was a time when HTML and HTTP were all that were needed to get the job done. And by job I of course mean a functional interface to the application. The client-server architecture that occupies the vast majority of what we interact with on the web works really well. The command response style of working with resources is simple, obvious, and well tested.