One UI is Samsung's design system for phones, tablets, watches, earbuds, and PCs, dividing screens into a viewing area up top and a reachable interaction zone below, tuned for large-screen and foldable devices.
It's strongest as a rare, well-documented example of a single design language spanning genuinely different device categories at once, phone, foldable, watch, and PC, with layout rules that specifically account for large-screen reachability rather than assuming a small phone screen throughout.
Designers building for foldables, wearables, or multi-device product families who want proven layout patterns for reachability across very different screen sizes.
The full design guide is available as a downloadable PDF directly from Samsung, useful for offline reference beyond the web documentation.
Samsung's One UI design system, unifying the experience across its devices.
