They have become an indispensable part of our everyday life: Brilliant graphical elements on displays with which we communicate daily: On our smart phones, in the car, on the refrigerator, coffee machine or washing machine. The menu of the user interface should be intuitive, effortlessly overcome cultural and linguistic boundaries, get us where we want to go quickly and be fun to interact with. This interface between people and machines makes our day-to-day lives easier. “Human Machine Interfaces” (HMIs) are reactive displays. They transmit our instructions and allow us to communicate directly with computers and machines.