One UI is a software overlay developed by Samsung Electronics for its Android devices. Succeeding Samsung Experience and TouchWiz, it is designed to be further streamlined, with specific optimizations to ease one-handed use of smartphones with large screens. It is also designed to be more visually comforting. To provide more clarity, some elements of the UI are tweaked to match the colours that are based on the colour of the user's phone. It was unveiled at Samsung's developer conference in 2018, and first introduced as part of Samsung firmware updates to Android 9 "Pie".