A user interface (UI) is everything a person sees and touches when using a piece of software or a device: screens, menus, buttons, text and the way they respond. It sits on top of the system's logic and data, which are often reached through an application programming interface. UI is closely tied to user experience (UX), the wider question of how easy and pleasant the product is to use. In finance and crypto, a clear UI does real safety work. A crypto wallet must show the amount, the network and the destination plainly before a user signs, because most blockchain transfers cannot be reversed. Decentralized applications usually offer a web front end over their smart contracts, and that front end can be changed or blocked even when the contracts keep running.
Last updated 13 Nov 2026