What is one interface decision that instantly improves usability?

A clear button label can make an application easier to understand. Better spacing can improve readability. A well-designed empty state can prevent confusion. A sensible hierarchy can make a complicated screen feel simple.

But different designers solve these problems in very different ways.

What UI or UX principle has made the biggest difference in your work?

Maybe it's consistency. Maybe it's reducing the number of choices presented at once. Maybe it's designing error states before happy states. Maybe it's making accessibility part of the process from the beginning instead of adding it later.

I'd also like to hear what designers think developers consistently misunderstand about interface design, and what developers think designers sometimes overlook.

How do you work with design systems? Do you prototype extensively before development, or iterate directly in the product? How do you handle mobile and desktop differences? How do you test whether an interface is actually understandable rather than merely attractive?

Share an interface you think is exceptionally well designed and explain why.

It doesn't have to be a famous product. A tiny application with a thoughtful interaction can teach more than an enormous polished product.