A human-machine interface is the part of a system people use to operate it: a touchscreen, knob, button panel, dashboard display, or control console. It translates human input into machine actions and returns status information, warnings, or feedback. In practice, HMI quality is about more than appearance; it determines whether users can understand and control a device quickly, accurately, and safely.
In cyber security, HMI matters because it is often the easiest place for an attacker to influence behavior or hide malicious activity. In industrial systems, vehicles, medical devices, and building controls, a compromised HMI can mislead operators, suppress alarms, or trigger unsafe actions. Defenders also rely on HMI design to reduce mistakes: clear prompts, limited permissions, and strong visual feedback help users spot anomalies and resist phishing, social engineering, or unauthorized commands. Good HMIs support secure operation by making the right action obvious and the dangerous action hard to miss.