This is the sample of an IFrame. Neat HUH?
As the page goes down...just as a normal page...the scroll bar gets longer. Only the page is brought up in the same page as the coding for the IFrame is on. It's a rather neat little way to get more information on one page without all the hassle of the scrolling on that same page.
It also works excellent for personal home sites (pages) to display disclaimers, copyrights etc. all on one page so that your viewers don't have to go searching for this information. However, a word of caution is to be given here...it does not work in all browsers and you will need to create links to them anyway so that all may view them.