The environment has a thousand faces. One is warm and smiling with the sun shining from a cloudless sky. Another is grey and sad with pouring rain and cold cloud filled skies. Conditions in the wilderness can be so varied that you may have to be prepared for smiling or sad in the same day.
Several layers of clothing allow you to add and remove garments and adjust your need for warmth and protection to the prevailing conditions.
Base layers must keep you warm and dry by wicking moisture away from your body. The garment could be either wool or synthetic fibre and for most efficient use, particularly in the winter, be close fitting.
The second layer of clothing should insulate and be suitable for low activity levels, breaks, and particularly cold days. These mid-layers can also be made from wool or fleece and depending on your chosen activity or location be a variety of thickness