UI (user interface) is a digital product's visual layer: layout, typography, colour, components and their states. Good UI realises the structure designed in UX and gives it the brand's character.
UI decides first impressions and whether we trust a product: research shows credibility judgements about websites form in fractions of a second and rest mostly on aesthetics.
The UI craft is systematic work on details: a consistent grid, typographic hierarchy, contrast that meets accessibility requirements, component states (hover, focus, error, loading), responsiveness, and micro-interactions that create a sense of fluidity.
Modern UI is designed in components – hence its natural bond with design systems. At Sweet Lava the UI layer is designed by Academy of Fine Arts graduates and implemented by engineers on the same team, so the final product looks exactly like the design.