User interface (UI)

Set of all the components of an interactive system that provide information and controls for the user to accomplish specific tasks with the interactive system.

ISO definition

Set of all the components of an interactive system that provide information and controls for the user to accomplish specific tasks with the interactive system.

Ergonomics of human-system interaction — Part 110: Interaction principles - external link

ACM CSS Concepts

Human-centered computing - external link

Human computer interaction (HCI) - external link