Trackball

For the game, see Trac Ball.
A Logitech trackball
The original version of the Kensington Expert Mouse can use a standard American pool ball as a trackball.[citation needed]

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.[1] 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.[2]

With most trackballs, operators have to lift their finger, thumb or hand and reposition in on the ball to continue rolling, whereas a mouse would have to be lifted itself and re-positioned. Some trackballs have notably low friction, as well as being made of a dense material such as phenolic resin, so they can be spun to make them coast. The trackball's buttons may be in similar positions to those of a mouse, or configured to suit the user.

Large trackballs are common on CAD workstations for easy precision.[citation needed] Before the advent of the touchpad, small trackballs were common on portable computers (such as the BlackBerry Tour) where there may be no desk space on which to run a mouse. Some small "thumballs" are designed to clip onto the side of the keyboard and have integral buttons with the same function as mouse buttons.[2]

  1. ^ "The Next Generation 1996 Lexicon A to Z: Track Ball". Next Generation. No. 15. Imagine Media. March 1996. p. 42.
  2. ^ a b This article is based on material taken from tracker+ball at the Free On-line Dictionary of Computing prior to 1 November 2008 and incorporated under the "relicensing" terms of the GFDL, version 1.3 or later.