Cascading Style Sheets is a technology that allows us to control the presentation of
webpages.
Here is a demonstration
The Before CSS button is an ordinary web page without CSS
The After CSS button is the same web page but with a CSS makeover.
What is more is that there are significant bandwidth savings if you use Cascading Style Sheets - CSS.
ESPN.com serves up more than half a billion page views every month,
when the home page of the site
dropped all layout tables in favor of structural markup and CSS-driven
layout their savings amounted to 730 terabytes a year.
see http://www.mikeindustries.com/blog/archive/2003/06/espn-interview for
more details.