Also reffered to as 'Flash' These dynamic websites are used to achieve a great flowing feel to your site. Pages pre-load before the user starts browsing so when you click on a link lets say the page will slide off and the page you requested will slide on.
With flash web animation as well as audio is easily achieved. The only real draw back of a complete flash site is that it requires flash media player to be installed! Your website browsers will have to download flash before viewing your site.