To many designers and developers the process of designing for mobile assumes that touch is natural, so we don’t need to pay any particular attention to the design of touch systems. This is not true. As children we all had to learn — for years — how to touch, feel, and manipulate real-world objects. Touchscreens and our standard paradigms of interaction are not the same as the real physical world; touchscreen behaviors are as learned as the use of a mouse or a doorknob.