What is a UI document?
A user interface specification (UI specification) is a document that captures the details of the software user interface into a written document. The specification covers all possible actions that an end user may perform and all visual, auditory and other interaction elements.
What are the top 3 most important things in a good UI design?
The UI design principals are:
Make it comfortable to interact with a product. Reduce cognitive load. Make user interfaces consistent.