Yes this article is a tad lengthy but its right to the point with full detail.
Johnie explains to us the importance of layering, it could be the difference of life or death. Or even how your time will be. She explains to us which layer does what and what kind of clothing we should and shouldn't wear for this layer. She also describes to us her preference for that layer.
After reading this article I know now the 3 basic layers, their rundowns, and the bottom line.