he user interface or human–machine interface is the part of the machine that handles the human–machine interaction. Membrane switches, rubber keypads and touchscreens are examples of the physical part of the Human Machine Interface which we can see and touch.
In complex systems, the human–machine interface is typically computerized. The term human–computer interface refers to this kind of system. In the context of computing the term typically extends as well to the software dedicated to control the physical elements used for human-computer interaction.
The engineering of the human–machine interfaces is enhanced by considering ergonomics (human factors). The corresponding disciplines are human factors engineering (HFE) and usability engineering (UE), which is part of systems engineering.
Tools used for incorporating human factors in the interface design are developed based on knowledge of computer science, such as computer graphics, operating systems, programming languages. Nowadays, we use the expression graphical user interface for human–machine interface