This chapter sets about to provide the background and orientation needed to set a novice designer on his or her way to bringing haptics successfully into an interactive product. To define appropriate roles for haptic interaction, it is necessary to integrate a basic awareness of human capabilities on one hand and current device technology on the other. Here, I explore this integration by first summarizing the most salient constraints imposed by both humans and hardware. I then proceed to relate perceptual, motor, and attentional capabilities to a selection of emerging application contexts chosen to be relevant to contemporary design trends and opportunities. These include abstract communication and notification, augmentation of graphical user interfaces, expressive control, affective communication, and mobile and handheld computing.Our touch (haptic) sense is such an integral part of our everyday experience that few of us really notice it. Notice it now, as you go about your business. Within and beneath our skin lie layers of ingenious and diverse tactile receptors comprising our tactile sensing subsystem. These receptors enable us to parse textures, assess temperature and material, guide dexterous manipulations, find a page's edge to turn it, and deduce a friend's mood from a touch of his hand. Intermingled with our muscle fibers and within our joints are load cells and position transducers making up our proprioceptive sense, which tell our nervous systems of a limb's position and motion and the resistance it encounters. Without these and their close integration with our body's motor control, it would be exceedingly difficult to break an egg neatly into a bowl, play a piano, walk without tripping, stroke a pet, write, draw, or even type.Touch is our earliest sense to develop (Montagu, 1986). It has evolved to work in a tight partnership with vision and hearing in many ways we are only beginning to understand, as we study processes (such as hand-eye coordination) and how we process conflicting or competing information from different senses.In stark contrast to the importance of touch in our everyday experience, the use of touch is marginalized in contemporary computer interfaces, overlooked in the rush to accommodate graphical capability in desktop-based systems. The primary advances have been in feel-focused improvements in nonactuated pointing tools for both function and aesthetics. Scroll wheels have been designed for the user to click with just the right resistance and frequency; and most cell phones now come with vibrators that indicate incoming calls. Meanwhile, the use of haptic feedback in the consumer sphere is largely limited to gaming, and tactile feedback to simple cell phone alerts. Downloaded from 2007), and open-source and proprietary software libraries ease their programming. Although a vast divide remains between the display fidelity of current haptic versus graphic technology, the entry level for utilizing haptic feedback has become much lower. But as always, coming up with a "killer app" is mor...