You can't have a website or app that works great, but looks like it was assembled with construction paper and paste. You also can't have a gorgeous web experience crippled by slow loads, bad links, and wonky navigation. Those are examples of what happens when the worlds of user experience (UX) and user interface (UI) [&]

https://boingboing.net/2020/08/22/get-100-hours-of-expert-led-ui.html