Concept UI designs are interface designs created to explore an idea rather than to ship a real product. A designer imagines how an app, website, or device could look and work, usually without a real client, real users, engineering limits, or business requirements. Common examples are the "Spotify redesign" or "banking app of the future" posts you see on Dribbble and Behance.

People make them for a few reasons. Designers without client work use them to build a portfolio and sharpen their visual skills in layout, typography, color, and motion. They also use them to try out a new interaction or style before anyone invests real time or money in it. Companies make concepts too, especially car makers and tech firms, to show where they're heading and to get teams aligned on a vision before detailed design begins.