Fleece is a soft, breathable synthetic (polyester) knit used as a warm, quick-drying mid layer. It insulates even when damp, breathes well for active use, and is durable and affordable, though it is bulky and not windproof. Fleece comes in weights from light grid fleece to heavy jackets.
A synthetic jacket is insulated with man-made fibers that mimic down, offering reliable warmth that — crucially — keeps insulating even when wet and dries fast. Synthetics are cheaper and more weather-tolerant than down but heavier and bulkier for the same warmth, making them ideal for damp climates and active use.
A down jacket is insulated with down — the soft, lofty plumage under bird feathers — giving the best warmth for its weight and packing down very small. Down's weakness is moisture: it loses loft and warmth when wet, so it excels in cold, dry conditions and is often paired with a shell or treated to be water-resistant.
A rain jacket is a waterproof, breathable outer layer designed to keep you dry in rain. It uses a waterproof membrane or coating and taped seams, with a DWR finish that makes water bead off the surface. Rain jackets range from light packable shells for emergencies to burly hardshells for sustained storms.
A softshell is a stretchy, breathable outer jacket that blocks wind and sheds light moisture while letting you move freely, ideal for active use in dry or variable conditions. Softshells trade the full waterproofing of a hardshell for comfort, breathability, and durability, making them popular for climbing, hiking, and ski touring in fair weather.
A hardshell is a fully waterproof, windproof outer jacket built to keep rain and snow out in serious weather, typically using a membrane like Gore-Tex with taped seams. Hardshells are tough and protective but less breathable and stretchy than softshells, making them the go-to for storms, alpine climbing, and wet conditions.
A shell is the outer layer of a clothing system, worn over insulation to block wind and rain. Shells range from waterproof hardshells for storms to breathable softshells for active use in dry, windy conditions. The shell protects the warm, dry layers beneath from the elements.
A mid layer is the insulating middle layer in a clothing system, worn over the base layer to trap warmth. Common mid layers include fleece, down, and synthetic-insulated jackets. You add or remove the mid layer to regulate temperature, making it the adjustable 'thermostat' of the layering system.
A base layer is the innermost clothing layer worn against the skin, designed to wick sweat away and keep you dry within the layering system. Made from merino wool or synthetics (not cotton), base layers regulate temperature and moisture; a dry base layer is the foundation of staying warm and comfortable outdoors.
A backpack is a fabric pack worn on the back to carry gear, with shoulder straps and usually a hip belt and frame to transfer load to the hips. Outdoor backpacks range from small daypacks to large multi-day packs measured in liters, and a good fit — load on the hips, not the shoulders — is the key to comfort.