Human-Machine Interface (HMI) is a system that enables interaction between humans and machines. It is the graphical user interface (GUI) that allows users to interact with electronic systems, such as computers, automated machines, and other digital devices, via input and output devices. HMI can be as simple as a button and as complex as a touchscreen with multiple interactive functions. It is used to convey information and commands to machines, as well as to display the output of the machines.