By Steve Tischler
This article is informative and is easy to understand. It explains the importance and the mechanics of layering in an easy to follow manner with pictures.
Base Layer: Moisture Management
In the first section, the author explains that the use of the base layer is to help regulate your body temperature by moving perspiration away from the skin to somewhere it can evaporate, the fact that it is good to have a base layer all year round to avoid overheating in the summer and to avoid hypothermia in the winter, and the types of material that are a good choice for a base layer (merino wool, synthetic fabrics and silk).
Middle Layer: Insulation
In this section, the article states that the insulating layer is used to trap the warm air around your body and keep it close. It also says that natural fibres, classic fleece, wind fleece, etc. are good choices for the middle layer.
Shell Layer: Weather Protection
In the last section, the author tells us about the outer layer. The shell layer is designed to keep wind and rain out, while letting the perspiration from the first layer evaporate. The article tells us about the different kinds of weather protection layers can be used and for what specific purposes. For example, a waterproof/breathable shell would be best suited for a wet, cool environment while doing alpine activities, whereas a waterproof/non-breathable shell would be ideal for a rainy day while fishing or watching outdoor sports.
The only thing that I would change about this article is that it is from a website that sells these types of products, so it advertises their products throughout the article, which I would prefer they not do. Other than the aforementioned, the article was interesting, informative and simple.
Web Address: http://www.rei.com/learn/expert-advice/layering-basics.html