User Interface

The Human-Machine Interface (HMI): the critical space where a user exchanges information with a system, enabling control via input and output elements.

User Interface (UI) technology dictates how a human operates a machine: it is the full interaction layer. This layer includes both physical hardware (touchscreens, keyboards) and software components (Graphical User Interfaces or GUIs). Effective UI design is paramount: it directly impacts system usability and user efficiency. Consider the difference between a simple Command-Line Interface (CLI), like a Unix shell, and a complex, icon-driven mobile OS (iOS, Android). The goal remains consistent: translate complex machine functions into intuitive, accessible controls for the end-user, minimizing friction and maximizing throughput.

https://en.wikipedia.org/wiki/User_interface