Human Machine Interfaces such as operator panels, touchscreens, keyboards, mice, and gamepads allow direct, physical input of data from the operator. Other terms for human-machine interfaces are man-machine interface (MMI) and, when the machine in question is a computer, human–computer interface. Additional UI layers may interact with one or more human senses including: tactile UI (touch), visual UI (sight), auditory UI (sound), olfactory UI (smell), equilibrial UI (balance), and gustatory UI (taste).