•enables the user to use a touchpad-like surface for keyboard input, cursor positioning, and gesture input •Advantages: Two-handed operation - manual advantages (increased time-motion efficiency because there are twice as many degrees of freedom available) and cognitive advantages (visualizing and composing the task).  Leganchuk et al (1999) found that bimanual techniques resulted in significantly faster performance than one-handed techniques. In addition, not limited in size or shape and frees the constraint of touch location