Mental BoundThe user interface is everything on the screen: buttons, forms, navigation, icons, and feedback like loading states or error messages. Strong UI is consistent — the same actions look and behave the same way across the product — and legible, with hierarchy that guides attention without overwhelming detail.
UI works hand in hand with UX. UX defines flows and priorities; UI expresses them in pixels and code. A clear visual system (design tokens, component libraries, spacing and type scales) helps teams ship faster and keeps the product coherent as it grows.
Accessibility is a core requirement for modern UI: sufficient contrast, focus indicators, semantic structure, and support for assistive technologies. Motion and delight matter, but they should reinforce clarity, not replace it.