A trackball is a pointing device consisting of a ball held by a socket containing sensors to detect a rotation of the ball about two axes—like an upside-down ball mouse with an exposed protruding ball. Users roll the ball to position the on-screen pointer, using their thumb, fingers, or the palm of the hand, while using the fingertips to press the buttons.
A Logitech trackball
The original version of the Kensington Expert Mouse can use a standard American pool ball as a trackball.[citation needed]
Logitech Cordless TrackMan Wheel
An Apple Pippin gamepad with a trackball
A pointing device is a human interface device that allows a user to input spatial data to a computer. Graphical user interfaces (GUI) and CAD systems allow the user to control and provide data to the computer using physical gestures by moving a hand-held mouse or similar device across the surface of the physical desktop and activating switches on the mouse. Movements of the pointing device are echoed on the screen by movements of the pointer and other visual changes. Common gestures are point and click and drag and drop.
A computer mouse
Touchpad and a pointing stick on an IBM notebook
Trackpoint
An elder 3D mouse