The basic thought is that you want to sweat as little as possible and stay dry as much as possible. To generate this your clothing must transport moisture away from the skin, hold dry warm air close to the body and keep rain and snow out. The three-layer-principle enables you to regulate your body temperature yourself by taking off or putting on garments as changing weather or intensity of work demand. Here is how it works from inside out:
FIRST LAYER THAT EFFICIENTLY TRANSPORTS MOISTURE AWAY FROM THE SKIN AND DISTRIBUTES IT TO THE OUTSIDE OF THE GARMENT.
PROVIDES INSULATION AND WARMTH WHILE TRANSPORTING MOISTURE AND EXCESS HEAT TO THE NEXT LAYER OR INTO THE AIR.
YOUR SHIELD AGAINST THE ELEMENTS WHICH PROVIDES COMFORT AND PERFORMANCE NO MATTER THE CONDITIONS.