user interface

Definition

A user interface (UI or U/I) is the space where interactions between humans and machines occur.

More on Wikipedia

The Reactable, an example of a tangible user interface In the industrial design field of human–computer interaction, a user interface (UI) is the space where interactions between humans and machines occur. The goal of this interaction is to allow effective operation and control of the machine from the human end, while the machine simultaneously feeds back information that aids the operators' decision-making process.
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