Wool
Wool is a stand-alone material that effectively traps dead air and uses it to insulate the body. Wool handles moisture, humidity and wet conditions exceptionally well. It absorbs moisture from the body and then releases it to the outside dry environment as your body warms, maintaining just the right amount of interior heat and dryness. However, if it becomes overly saturated it would need to dry out before being comfortable to wear outdoors again.
It is a quick-drying material. It is odor-resistant, due to its moisture-wicking properties. Bacteria that create odors cannot thrive where there is a lack of moisture. Furthermore, wool has incredibly strong fibers that can be stretched and pulled many times over without damage or becoming misshapen. Merino wool is higher-end wool that is finer than typical wool, creating a softer, less itchy fabric. Its fine fibers also make it even quicker to dry.
Fleece
Fleece is another stand-alone material. It is warm, similar to wool, but it is much lighter and thinner. It is non-bulky, soft and lightweight. Fleece is versatile and easy to use as a mid layer in colder temperatures or as an outer layer in milder ones.
Down and Synthetic Down
Down and synthetic down is not a material, but fine fibers used as the inner insulation in clothing and other items such as coats, vests, and blankets. They are warm, desirable insulation for winter days. Down tends to be more warm than synthetic, but it does clump without easily returning to its natural shape when wet. Synthetic is not as warm as down but doesn’t clump when moisture saturates it. Both are incredibly effective and highly used insulators in winter wear.