"UI" or User Interface is the point of which the information of the 
website page is viewed.

In order to attrack or keep your clientel on the site is to make the 
information easy to get too. A well organized site is a good site, the
easier it is to find crucial information the better off your site will be.

Bright colors, and over advertising is bad for user interface. Try to
keep everything simple. Advertising has it's place and most of the 
time it's on the right column. The below diagram was provided to 
give you an idea of how the orginization should be, and or stay. 
Some companies like to present there information in artsy ways using
flash and other components that are not necessarily good for
web crawlers. this moves away from good content, and easy
navigation, and can sometimes be useless when needing good stats.