If you have an IBM-compatible computer, the amount of use you'll get out of the second or third mouse buttons depends on the program you're using and your operating system. Windows 95 in particular makes extensive use of the button on the right-hand side of the mouse. Although most computer users are happy with mice, there are a variety of alternatives. Next to the mouse, trackballs are the most popular pointing devices. Users like them because they don't take up as much room on the desktop and require less arm movement.
Trackballs are like mice turned upside down.
Instead of rolling across the desktop, the ball faces upward and you turn it with your fingers, thumb or entire palm, depending on the size of the unit. Trackball fans say they get more control of the mouse pointer with less arm fatigue than they do with a mouse. Because they're small and stationary, trackballs are frequently built into laptop computers. On the downside, trackballs can be thrown out of kilter by the oil from your skin and have to be cleaned frequently. Touch pads .