An Operator panels is the user interface that connects an operator to the controller for an industrial or technical system. HMIs translate data from industrial control systems into visual representations of the systems. On the HMI, an operator can see schematics of the systems and interact with different parts of a process e.g. turn switches and pumps on or off, raise or lower temperatures, etc.

The interaction between operator and machine happens most often directly on the touch screen of the HMI, but are in some cases combined with keypads, function keys or external keyboards. HMIs are usually able to communicate directly with a variety of programmable logic controllers (PLC) and other industrial controllers, and additional cloud connectivity is an increasing trend for newer HMIs. HMIs are often offered as off-the-shelf products, however, with several additional options and some possibilities for customization.