Preface
The most annoying part of using any website or web application is the time we wait for pages to load. Sure, everybody is working on making the Web fast, but those 2-3 seconds that it takes for a round trip to the server does not stop you from opening multiple tabs and often forgetting which tab you originally were on.
The rapid popularity of JavaScript frameworks and technologies such as AJAX clearly show the desperate need to save those 1 or 2, second-round trips to the server, and provide the users with a more desktop-like user experience.