An HMI is the screen, dashboard, or control panel operators use to monitor and manage industrial equipment. In water plants and other industrial settings, the HMI shows process values, alarms, trends, and control buttons for systems such as pumps, valves, and treatment units. It is the point where human decisions meet machine actions.
HMIs matter in cyber security because compromise can give attackers a simple path from network access to operational impact. If an attacker reaches an HMI through weak passwords, exposed remote access, or poor segmentation, they may change setpoints, disable alarms, or hide abnormal conditions. Defenders protect HMIs by limiting who can access them, isolating them from public networks, using strong authentication, and monitoring for unusual logins or configuration changes. In practice, an HMI is both a visibility tool and a critical attack surface.