I think Jonathan Lampel does a far better job than I can in: https://cgcookie.com/lessons/smooth-flat-and-custom-normals
You’ve probably seen it already, but now is the time to re-watch it and understand better what it means.
There was a question on the forum some time ago, about why the Auto Smooth Angle field was greyed out and it took me over an hour to figure it out…now, I know where to look and I also had to revisit mentioned Lesson, because I didn’t know exactly what was happening.
But of course, feel free to ask, if you want more information, after watching Jonathan’s explanation.
