Pointing in human-computer interaction consists of moving a cursor onto text or a graphical object with an input device and clicking a button . Pointing is a fundamental operation in modern graphical user interfaces. Selecting a pointing device can have important implications for some computer users with disabilities. Clients with limited upper arm motion (particularly high-level spinal cord injury [SCI], multiple sclerosis [MS], or amyotrophic lateral sclerosis [ALS]) may not use a keyboard at all and may rely entirely on their pointing device (or a combination of their pointing device and speech recognition) for computer access. For these clients, choosing the wrong pointing device, or failing to properly configure the pointing device, can create unnecessary barriers to success. For all computer users with disabilities, providing access to the most appropriate pointing device can significantly increase efficiency while reducing frustration and fatigue.