Layering is the practice of dressing in several jackets or other layers so you’re ready for a variety of winter conditions. With layering, you can avoid buying “too much jacket.” Instead, you can augment what you have with additional layers.People who engage in strenuous winter activities appreciate layering because they can add or shed layers as needed. Layering typically involves three separate tiers: a base (thermal underwear or similar) to help wick sweat; an insulating mid-layer to keep you warm, such as fleece or a light jacket; and an outer layer, often thin, to shield you from wind and rain.