What is sense ui?

Sense UI is what you see on the 7 home screen pages. The clock, weather, etc... It can be turned off in your settings and then you will have a bare bones looking Android.
 
Not that I want to turn off sense UI, it is (part of) what makes the Eris such a slick phone, but how do you turn in off (ie where in the settings).

thanks
-spg