interaction
UI (user interface)
The tangible surface a person sees and touches – layout, type, colour, icons, buttons, motion.
Everything on screen you can point at is UI: the typography, the colour system, the buttons, the spacing, the animation. It’s the walls, door handles and light switches of the product-as-house – the part you can literally see and physically interact with.
UI is where the whole visual vocabulary of The Eye lives. It is not the whole experience – a screen can be beautiful and the product around it still miserable to use. That gap has its own name: UX.