In addition to moving a cursor, computer mice have one or more buttons to allow operations such as selection of a menu item on a display. Though originally all mice were connected to a computer by a cable, some modern mice are cordless, relying on short-range radio communication with the connected system. Most modern mice use optical sensors that have no moving parts. Later, the standard design shifted to utilise a ball rolling on a surface to detect motion. Mice originally used two separate wheels to track movement across a surface one in the X-dimension, and one in the Y. The first public demonstration of a mouse controlling a computer system was in 1968. This motion is typically translated into the motion of a pointer on a display, which allows a smooth control of the graphical user interface of a computer. A computer mouse (plural mice, rarely mouses) is a hand-held pointing device that detects two-dimensional motion relative to a surface.
