A scroll bar is a structure to the right of a window or control that can be used to shift the contents vertically, or at the bottom of a window to shift the contents horizontally. A scroll bar has an arrow structure at either end that will scroll the contents by one unit (e.g. one line if the contents is text) and a moveable control (known as a thumb) that can be dragged to make larger movements. Movements of one page (the exact meaning of which depends on the window contents) can be made by clicking above or below the thumb (see %hx and %vx).