Consider a door with a handicap button. The interface is: press button, door opens. Now consider a door with a motion sensor, the new interface is: walk towards

Consider a door with a handicap button. The interface is: press button, door opens. Now consider a door with a motion sensor, the new interface is: walk towards door, door opens. This is basically an example of eliminating an interface. You rarely think about these interfaces because they just do the right thing. Many very simple operations have interfaces, and you can sometimes streamline or remove those interfaces using simple mechanisms.