A scroll wheel is a wheel used for scrolling. The term usually refers to such wheels found on computer mice. It is often made of hard plastic with a rubbery surface, centred around an internal rotary encoder. It is usually located between the left and right mouse buttons and is positioned perpendicular to the mouse surface. Sometimes the wheel can be pressed left and right, which is actually just two additional macros buttons.

A computer mouse is a hand-held pointing device that detects two-dimensional motion relative to a surface. This motion is typically translated into the motion of the pointer on a display, which allows a smooth control of the graphical user interface of a computer.