An insulated jacket, or 'puffy', is a jacket filled with down or synthetic insulation that traps warm air to keep you warm. Worn as a mid layer or an outer layer at rest, it's the standard way to add warmth outdoors. The key choice is down (warmest for weight) versus synthetic (warm when wet).
Pack volume is a backpack's carrying capacity, measured in litres. It's the main way packs are sized: roughly 10-30 L for day hikes, 30-50 L for lightweight overnights, 50-70 L for multi-day backpacking, and 70 L+ for expeditions. The right volume depends on trip length, season, and how bulky your gear is.
Load lifters are the straps running from the top of the shoulder straps up to the top of the pack frame, used to pull the load closer to your body for balance and to fine-tune how weight sits. Adjusted to roughly a 45-degree angle, they keep a heavy pack from pulling you backward.
A hip belt is the padded waist belt on a backpack that transfers most of the load from the shoulders to the hips, where the body carries weight far more comfortably. On a loaded pack the hip belt should bear the majority of the weight — getting its fit and position right is the single biggest factor in carrying comfort.
An external-frame pack mounts the pack bag on a rigid, visible frame, holding the load high and away from the back. The classic design favored before internal frames, it carries heavy loads efficiently, ventilates the back well, and makes lashing on bulky gear easy, but is less stable on steep or uneven terrain.
An internal-frame pack carries its support structure — stays, framesheets, or rods — inside the pack body, hugging the load close to your back for stability on uneven terrain. The dominant modern backpack design, it excels at balance for scrambling, skiing, and rough trails, though it ventilates less than an external frame.
A daypack is a small backpack, typically 10-30 litres, used for day hikes and short outings where you don't carry overnight gear. It holds the essentials — water, food, layers, and the Ten Essentials — and is light and simple, often without the frame or heavy hip belt of a multi-day pack.
Layering is the system of wearing multiple clothing layers — a wicking base layer, an insulating mid layer, and a protective shell — that you add or remove to regulate temperature and moisture outdoors. Layering lets you adapt to changing weather and exertion, and is the foundational principle of dressing for the backcountry.
Microspikes are lightweight traction devices — elastic harnesses with small chain-mounted spikes — that slip over shoes or boots for grip on packed snow and icy trails. Far lighter and less aggressive than crampons, they're ideal for winter hiking and trail running on rolling terrain, but not for steep snow or ice climbing.
A headlamp is a head-worn light that frees your hands for tasks in the dark — hiking before dawn, setting up camp, or navigating at night. Measured in lumens for brightness, modern LED headlamps offer multiple modes and run on disposable or rechargeable batteries. It is one of the Ten Essentials.