Gates used the moues for the basis of a Microsoft Windows program that could only be navigated through by the mouse. The mouse has many useful purposes. It is a locating device that is used for indicating a position for placing objects on the screen or quickly moving the cursor in a text editor. It can be either physical or optical. The physical mouse has a ball that protrudes from it's bottom.
Friction causes the ball to move at a rate proportional to the movement of the mouse.
It has a set of potentiometers that sense the direction and rate of the movement of the ball. Then it is converted into electrical signals that are interpreted by the computer signifying that the mouse is in motion. The mouse pad is key to operate the mouse. It is a reflective surface with a set of light and dark horizontal and vertical lines. The light from the LED reflects off the mouse pad to the sensor.