Most web applications these days use a lot of JavaScript to give a web page an application-like feel. However, many of them, like Gmail for example, also provide a "Basic HTML" mode. Choosing this option will sacrifice neat-o functionality for a more streamlined and faster-loading experience. In general, you'll miss out on drag-and-drop mouse actions, automatic content refreshes and things like chat, but your pages will be faster and they will work better in less capable browsers.