My last post was about User Experience design so I thought I'd discuss its counterpart, UI design here.

The following is an example of both good UI and UX from Basecamp

As the user completes fields the hand points to the relevant fields (UI), if a field is invalid then it outlines in red with a note of why it's invalid (UX). As a little twist the expression of the face changes with an invalid result, this could be considered a UX improvement but in reality it does not particularly add to the usability of the website as such I'd classify it as UI design.