This was a nice concise article and I thought most of the description was was on target. However, when describing the word “products” one should distiguish the difference between, digital and analog interfaces. The descriptive use and training of using a pencil is apt (not app), but there are distinctions between things we physically engage with and things we cognitively engage with. This distiction is becoming more critical in assessing interface and interaction through “mental” and “conceptual” modeling, especially in design. User interfaces are becoming more and more ubiquitous, to some generations, but there are some that still get stuck at the power button.