This is a common page navigation device. It is a narrow, tall box area to the right of the main content window. Within the box, there lies a darker box that you can drag up and down to move through the page.
If you click on the arrow icon at the top of the scroll bar, you can scroll directly to the top of the page, and the arrow icon at the bottom allows you to jump to the bottom of the page.
Challenge see if you can find out one extra fact on this topic that we haven't already told you
Click on this link: Scroll Bar