The technology used to help users interact with a computer system such as a touch screen or microphone.

For example…

Let’s take Kelly’s brainchild business, Modern Fashions. Kelly plans to offer a service in her clothing retail outlet that will let users upload photos of their accessories they plan to accompany an outfit the store sells into a simulator and the image is superimposed on the person trying on the outfit to give a clearer picture of their complete outfit. The user interface for the simulator includes touch screens and microphones as well as graphics and text displayed on the screen which provides the means of communication for the system.