The document discusses the evolution of user interfaces from command line interfaces (CLI) to graphical user interfaces (GUI) to natural user interfaces (NUI). It notes that as mobile devices and touchscreens became popular in the late 2000s, usage of personal computers declined while mobile app usage increased. The document outlines several technologies that enabled more natural interfaces, such as gesture and motion control, and provided examples of interfaces using these technologies. It argues that future interfaces will become even more natural and context-aware as new technologies are incorporated.