Test ajaxed functionality by adding up two number on server side using AJAX. Enter two numbers and press calculate to get the total. You will see that the page is not reloaded. Also recognize the "loading" indicator at the top right of the page.
Ajaxed also supports loading whole HTML fragments. This functionality is called "page parts". Page parts are simply sub's in your code which return HTML. This markup is then inserted automatically into a container of your choice. See a simple example: