A vertical bar on the right side of an on-screen window or a horizontal bar at the bottom of the window that is used to move the window's contents up, down, left or right. When dragged with a mouse or if a touchscreen is used, a finger, the window's contents moves correspondingly.
Somewhat Obsolete
Since the advent of scroll mice, which use a physical wheel for scrolling, the scroll bar is being used less and less on desktop applications. In addition, tablet and smartphone content is scrolled by fingers, and a scroll bar is not part of the interface. See
scroll mouse.
Scroll Bars
Clicking within the bar or dragging the thumb moves the contents within the window. The Mac example (right) shows an optional variation that places both scroll arrows in the same vicinity to lessen mouse movement when switching directions.