What is user interface (UI) design?

A user interface (UI) is the point of interaction between the user and a digital product or service. User interface design focuses on the series of pages, visual elements (like colour, layout and typography) and components (like icons, buttons and forms),  that a user interacts with when using a digital product or service.

UI design takes care of the look and feel, the presentation and interactivity of a product and it supports (and expands) the underlying UX work. The goal of UI design is to  visually guide the user through a product’s interface.