Glossary

The hiking gear glossary

Gear listings are written in a language nobody teaches you. These are the 134 terms that turn up in our buying guides, each with its own page and a straight answer at the top.

Jump to a section

Fit and sizing Backpacks Footwear Fabrics and waterproofing Sleep systems Shelters Stoves and water Trekking poles Lighting and electronics Bears and food storage Navigation and safety Trail terms

Fit and sizing

Torso length: Torso length is the distance from the bony bump at the base of your neck down to the top of your hip bones. It's the measurement backpack sizes are built around, and it has almost nothing to do with how tall you are.
Iliac crest: The iliac crest is the curved top edge of your pelvis, the ridge you feel when you put your hands on your hips. It's the shelf a backpack hipbelt sits on, and the lower anchor point for measuring torso length.
Last: A last is the foot-shaped mould a shoe or boot is built around. It sets the width, the volume, the shape of the toe box and the heel cup, which is why two pairs in the same size from different brands can fit completely differently.
Toe box: The toe box is the front of a shoe, from roughly the ball of the foot forward. Its width and height decide whether your toes can splay under load, which is what stops black toenails and blisters on long descents.
Surgeon's knot: A surgeon's knot is a lacing trick where you wrap the laces twice instead of once before pulling tight. The extra wrap holds tension in place, letting you lock your heel down while leaving the toe box loose.
Gusseted crotch: A gusseted crotch is an extra diamond or triangle of fabric sewn into hiking pants so four seams do not meet at a single point. It spreads the load of a high step across several seams, which is why gusseted pants do not bind or split at the crotch.
Short liner: A short liner is the brief, boxer or compression layer sewn inside running shorts and worn instead of underwear. Its cut is what decides whether long runs chafe: a brief covers little, a boxer liner reaches the inner thigh, and a 2-in-1 anchors to the shell so it cannot ride up.
Inseam: Inseam is the length of a garment's inner leg seam, measured from the crotch to the hem, and it is how running shorts are sized. Trail shorts run from about three inches to nine, and five to seven covers most trail running.
Chafing: Chafing is skin worn raw by repeated friction, usually where wet fabric rubs skin or skin rubs skin over hours. On a run it starts at the inner thigh, and dried sweat leaves abrasive salt behind that makes it considerably worse.

Backpacks

Load lifters: Load lifters are the short straps running from the top of the shoulder harness back to the top of the pack frame. They pull the load in towards your body so it stops levering you backwards. They don't carry weight themselves.
Hipbelt: The hipbelt is the padded belt that wraps your pelvis and transfers pack weight onto your hips instead of your shoulders. On a loaded backpacking pack it should be carrying most of the weight, often quoted as 70 to 80 percent.
Framesheet: A framesheet is a sheet of stiff plastic in a pack's backpanel that spreads the load across your back and stops contents from poking through. It's lighter than a frame but gives you less vertical support.
Internal frame: An internal frame is the structure hidden inside a pack's backpanel, usually one or two aluminum stays or a perimeter hoop, that carries weight from the shoulders down to the hipbelt. It's what makes a pack load-bearing.
Suspended mesh backpanel: A suspended mesh backpanel stretches a taut mesh across a curved frame so the pack body sits away from your back with an air gap behind it. It's the coolest-running backpanel design and the one that holds the load furthest from your spine.
Pack lid: The lid, or brain, is the padded flap that covers the top of a top-loading pack, usually carrying one or two zipped pockets. A floating lid is one attached by adjustable straps so it can rise as the pack is overfilled.
Extension collar: An extension collar is the fabric tube above a top-loading pack's main compartment, closed by a drawcord. Rolled down it does nothing; pulled up it adds capacity, typically 5 to 10 liters beyond the pack's quoted volume.
Panel loader: A panel loader opens with a zip that runs around the front of the pack, so the whole compartment folds open like a suitcase. The alternative is a top loader, which you access through an opening at the top.
Shove-it pocket: A shove-it pocket is the open-topped stretch panel across the front of a pack. It has no zip, so you can push a wet jacket or a map into it one-handed while walking, and pull it out just as fast.
Load rating: A load rating is the weight a pack maker says a pack carries well, usually given as a range in pounds. It describes the frame and hipbelt rather than the fabric, so exceeding it doesn't break the pack, it just moves the weight to your shoulders.

Footwear

Lug depth: Lugs are the raised blocks on the sole of a boot or trail shoe, and lug depth is how tall they are, usually 3 to 6 mm. Deeper lugs bite into soft ground; shallower ones give more contact area on rock and hard trail.
Outsole: The outsole is the rubber layer on the bottom of a shoe, the part touching the ground. It carries the lug pattern and the rubber compound, which together decide grip, and it's usually the first part of a shoe to wear out visibly.
Midsole: The midsole is the foam layer between the outsole and your foot. It absorbs impact and sets how stiff or soft a shoe feels, and it's the part that quietly dies long before the tread looks worn.
EVA foam: EVA is the light, springy foam most hiking and running midsoles are made of. It cushions well and weighs little, but it compresses permanently over time, which is why shoes go flat after a few hundred miles.
Stack height: Stack height is how much material sits between your foot and the ground, measured in millimetres at the heel and forefoot. More stack means more cushioning and less ground feel; less means more feedback and a lower, more stable platform.
Heel-to-toe drop: Drop is the height difference between a shoe's heel stack and its forefoot stack, given in millimetres. Zero drop means the foot sits level; 8 to 12 mm tilts you forward slightly and shortens the load on the calf and Achilles.
Rock plate: A rock plate is a thin stiff sheet, usually TPU or a nylon composite, embedded in the forefoot of a shoe. It spreads the load from a sharp rock across the whole foot instead of letting it press into one point.
Shank: A shank is a stiffening insert running through the arch of a boot, made of steel, nylon or composite. It controls how much the boot twists and bends, which is what lets a boot support a heavy load and edge on rock.
Rand: A rand is a strip of rubber bonded around the lower edge of a boot's upper, most often at the toe. It takes the abrasion from rock and roots that would otherwise wear through fabric or leather, and it protects your toes from impact.
Gusseted tongue: A gusseted tongue is sewn to the sides of the boot with fabric panels instead of hanging free. It seals the gap along the laces so grit and water can't get in, and it stops the tongue sliding sideways as you walk.
Vibram Megagrip: Megagrip is a Vibram rubber compound formulated for grip on wet and dry rock. It's softer and stickier than standard hiking rubber, which is why it holds on slabs and greasy roots, and why it wears out faster.
Gaiters: Gaiters are fabric sleeves worn over the top of a shoe or boot to keep grit, snow and water out. Low trail gaiters cover the collar and stop scree filling your shoes; tall gaiters run to the knee and seal the leg against deep snow and wet brush.
Microspikes: Microspikes are elastomer harnesses with short chains and spikes, roughly 10 to 15 mm, that stretch over a shoe for traction on packed snow and ice. They are the middle rung between yaktrax-style coils and full crampons, and they are not mountaineering equipment.
Crampon: A crampon is a metal frame carrying 10 or more points up to 5 cm long that binds rigidly to a stiff-soled boot, so a climber can stand on hard alpine ice and steep snow. It is the tier above microspikes, and it is technical equipment that needs an ice axe and training.
Insulation weight in grams: Insulation weight is the mass in grams of one square meter of the insulating sheet inside a boot or glove. A 400g boot uses a heavier sheet than a 200g boot, so it is warmer, but it is nothing like twice as warm.
Vibram Arctic Grip: Arctic Grip is a Vibram outsole technology built for traction on wet ice. It stays pliable at temperatures where ordinary hiking rubber goes hard, which is the reason a winter sole grips where a three season one skates.
Flotation: Flotation is how well a snowshoe keeps you on top of snow instead of sinking into it. It is a function of deck surface area measured against your loaded weight, which is your body plus clothing, boots and everything in your pack.
Heel lift: A heel lift is a small wire or plastic bar behind the heel of a snowshoe that flips up so your boot rests on it during a climb. It stops your calf being held at full stretch on sustained steep ground.

Fabrics and waterproofing

DWR: DWR is a chemical finish applied to the outside of a rain shell so water beads up and rolls off instead of soaking into the face fabric. It wears off with use and washing, and reviving it is routine maintenance rather than a repair.
Waterproof-breathable membrane: A waterproof-breathable membrane is a thin film bonded inside a shell fabric with pores small enough to block liquid water but large enough to pass water vapour. It's what makes a rain jacket different from a plastic poncho.
Gore-Tex: Gore-Tex is a brand of waterproof-breathable membrane made by W. L. Gore & Associates, and the name most people know the technology by. Gore licenses it to clothing makers under strict construction rules rather than selling finished garments.
ePTFE: ePTFE is expanded polytetrafluoroethylene, the microporous film at the heart of the original Gore-Tex and several competing membranes. Stretching PTFE creates billions of pores per square inch that block liquid water and pass vapour.
Hydrostatic head: Hydrostatic head measures how much water pressure a fabric holds before it leaks, expressed as a column height in millimetres. A 20,000 mm rating means a 20-meter column of water sat on the fabric before the first drops came through.
MVTR: MVTR measures how much water vapour passes through a fabric in a day, given in grams per square meter per 24 hours. Higher numbers mean a more breathable fabric, with most hiking shells landing between 10,000 and 25,000.
RET: RET measures how much a fabric resists the evaporation of sweat, tested under ISO 11092. It runs the opposite way to most ratings: lower is better, with under 6 counting as extremely breathable and over 20 as barely breathable at all.
Wetting out: Wetting out is when a shell's outer fabric absorbs water instead of shedding it, because the DWR finish has worn off. The membrane still blocks rain, but breathability collapses and the jacket feels like it's leaking from the inside.
Seam tape: Seam tape is a waterproof strip heat-bonded over the stitch line inside a garment or tent. Every needle hole is a hole in the waterproofing, so a shell with an untaped seam leaks there regardless of how good the fabric is.
2L, 2.5L and 3L laminates: These describe how many layers are bonded together in a shell. 2L has a loose liner hanging inside, 2.5L prints a protective pattern straight onto the membrane, and 3L bonds a fabric backer to it. Durability and next-to-skin feel go up with each step.
Denier: Denier is the weight in grams of 9,000 meters of a yarn, written as a number followed by D. It describes how thick the individual threads are, so higher denier usually means a heavier, tougher fabric, though weave and material matter too.
Dyneema Composite Fabric: Dyneema Composite Fabric is a non-woven laminate of UHMWPE fibers sandwiched between polyester films. It is waterproof from the moment it is made, does not stretch or sag when wet, and is the lightest shelter material in common use, at several times the price.
Ripstop: Ripstop is a weave with thicker reinforcing threads laid in at regular intervals, forming the faint grid you can see on tent and pack fabric. The grid does not stop a tear starting, it stops one that has started from running across the whole panel.
Silnylon: Silnylon is ripstop nylon impregnated with silicone on both faces, the standard fabric for lightweight tents and tarps. It is strong and cheap for its weight, and it stretches when wet, which is why a silnylon shelter sags overnight and needs retensioning.
PU coating: A PU coating is a polyurethane layer applied to the inside of a tent, pack or stuff sack fabric to make it waterproof. It is cheap, takes seam tape well and is what most budget shelters use, and it breaks down with age in a way silicone does not.
Cordura: Cordura is a brand of high-tenacity nylon fabric known for abrasion resistance, used where a pack meets rock and grit. It is a specification a mill licenses rather than a single fabric, so Cordura appears in weights from light shelter cloth to heavy pack bottoms.
Softshell: A softshell is a stretchy woven fabric with a brushed or knitted backing that blocks wind and sheds light rain while still breathing hard. It replaces a rain shell on cold, dry, windy days and is the standard fabric for technical hiking pants.
Base layer: A base layer is the garment worn directly against your skin under everything else. Its job is moving sweat off your skin so it evaporates somewhere other than on you, which is why warmth is a secondary consideration and cotton is disqualified.
Merino wool: Merino wool is fine-diameter wool from Merino sheep, spun for next-to-skin clothing at roughly 17 to 19.5 microns. That fineness is what stops it prickling, and it brings odour resistance and warmth when damp at the cost of abrasion life.
Fabric weight (gsm): Fabric weight in gsm is the mass of one square meter of the cloth, in grams. On a base layer it is the single number that sets the temperature window: about 150 gsm for warm weather, about 200 gsm for three-season hiking, 280 and up for cold.
UPF: UPF, or Ultraviolet Protection Factor, rates how much ultraviolet radiation a fabric blocks. A UPF 30 garment lets about one thirtieth of the UV hitting it through, so it blocks roughly 96.7 percent; UPF 50 lets one fiftieth through, or 98 percent.

Sleep systems

R-value: R-value measures how well a sleeping pad resists heat escaping into the ground. Higher numbers insulate better, and since 2020 every brand has tested to the same standard, so the numbers finally compare across brands.
Fill power: Fill power measures the loft of down: how many cubic inches one ounce expands to fill. Higher fill power traps more air per unit of weight, so an 850 fill bag is lighter and more compressible than a 650 fill bag of the same warmth.
Fill weight: Fill weight is how much insulation is actually inside a sleeping bag or jacket, given in grams or ounces. Paired with fill power it tells you what a bag's warmth is made of, and it's the number brands are least keen to publish.
Hydrophobic down: Hydrophobic down is down treated with a water-repellent finish so it resists moisture, dries faster and keeps some loft when damp. It delays the failure that untreated down suffers when wet, but it doesn't make down behave like synthetic.
EN/ISO temperature rating: EN/ISO is the standardised lab test that gives sleeping bags their temperature ratings. It produces several figures, and the two that matter are comfort, aimed at a standard cold sleeper, and limit, aimed at a standard warm sleeper.
Mummy bag: A mummy bag is a sleeping bag cut wide at the shoulders and narrow at the feet, with a hood that closes around your head. The taper leaves less air inside for your body to heat, which is why it is the warmest shape for its weight.
Draft collar: A draft collar is an insulated tube around the neck opening of a sleeping bag, cinched to seal the gap at your shoulders. It stops warm air pumping out of the top of the bag every time you move, which is where most heat is lost.
Baffle: A baffle is a fabric wall sewn between the inner and outer shells of a down bag to hold the down in place. Without baffles the down migrates to the low side and leaves cold spots where there's no insulation at all.
Footbox: The footbox is the shaped end of a sleeping bag or quilt where your feet sit. It's built with extra volume so the insulation isn't crushed flat by your toes, which is the coldest spot in most sleep systems.
Backpacking quilt: A backpacking quilt is a sleeping bag with the back removed and no hood, strapped to your sleeping pad instead. It cuts weight and bulk by deleting insulation that a bag crushes flat underneath you and that does nothing there anyway.
Pad attachment system: A pad attachment system is whatever keeps your bag or quilt joined to your sleeping pad, usually elastic straps that pass under the pad and clip to the quilt. It stops the two separating in the night on any surface that isn't flat.
Underquilt: An underquilt is an insulated quilt that hangs on the outside of a hammock, cradling it from below. Because your body never lies on it, nothing compresses the loft, which is why it works where a sleeping bag underneath you does not.

Shelters

Freestanding tent: A freestanding tent holds its shape on its own poles without needing stakes to stand up. You can pitch it on rock or a wooden platform, pick it up to move it, and shake it out, none of which a staked shelter allows.
Trekking-pole tent: A trekking-pole tent uses the poles you're already carrying as its structure, so it ships without a pole set. That removes a pound or more from the pack, and requires stakes and taut guylines to stand up at all.
Vestibule: A vestibule is the covered space between a tent's inner door and its fly, outside the sleeping area but under shelter. It's where boots, packs and wet gear live, and where you can cook in bad weather if you're careful.
Footprint: A footprint is a shaped sheet of fabric that goes under a tent to protect the floor from abrasion and punctures. It's almost always sold separately, and a piece of polycryo or Tyvek does the same job for a fraction of the weight and cost.
Trail weight: Trail weight, sometimes called minimum weight, counts only a tent's essential parts: inner, fly and poles. Packed weight counts everything in the box, including stakes, guylines, stuff sacks and instructions. The gap is usually several ounces.
Bathtub floor: A bathtub floor is a tent floor whose waterproof fabric curves up the sides several inches before meeting the walls, so the seams sit above ground level. Water running under the tent has no seam to get through.
Gathered-end hammock: A gathered-end hammock is a flat rectangle of ripstop nylon bunched to a single point at each end and hung from two trees. It is the standard camping design, and it only lies flat if you sleep diagonally across it rather than down the middle.
Structural ridgeline: A structural ridgeline is a fixed length of cord tied between a hammock's two gathered ends. Because it cannot stretch, it holds the hammock at one repeatable amount of sag no matter how far apart the trees are, so the bed feels the same at every campsite.
Double-wall tent: A double-wall tent is built as two separate layers: an inner body, usually largely mesh, and a waterproof rainfly over it. Condensation collects on the underside of the fly instead of on the surface you and your bag are touching.

Stoves and water

Canister stove: A canister stove screws directly onto a sealed cartridge of pressurised isobutane-propane. It lights instantly, simmers well and needs no priming, which is why it's the default backpacking stove almost everywhere fuel canisters are sold.
Integrated stove system: An integrated stove system pairs a burner with a matched pot that locks on, usually with a heat exchanger ring on the base. It boils water faster and uses less fuel than a separate stove and pot, at the cost of versatility.
Regulated valve: A regulated valve holds a stove's fuel pressure steady as the canister empties or cools. Without one, output drops off through the canister's life and falls sharply in the cold; with one, the flame stays consistent much further down.
Isobutane-propane blend: Isobutane-propane is the fuel blend inside standard threaded backpacking canisters, usually around 80 percent isobutane and 20 percent propane. Propane provides cold-weather pressure, isobutane provides most of the burn time.
Hollow fiber filter: A hollow fiber filter passes water through a bundle of tiny straw-like tubes whose walls are perforated with pores around 0.1 to 0.2 microns. It's the technology in almost every modern backpacking filter, and a single freeze can destroy it invisibly.
Micron rating: A micron rating states the largest particle a filter lets through, in microns. Backpacking filters are typically rated 0.1 or 0.2 microns, which stops bacteria and protozoa. Viruses are around 0.02 microns and pass straight through.
Flow rate: Flow rate is how fast a filter delivers clean water, usually quoted in liters per minute. The advertised figure is measured on a brand-new filter with clean water, and real flow drops as the element clogs with sediment.
Backflushing: Backflushing pushes clean water backwards through a filter to dislodge the sediment clogging its pores. It's routine maintenance on a hollow fiber filter, and it's the difference between one that lasts a season and one that lasts years.
Purifier vs filter: A filter physically strains out bacteria and protozoa. A purifier also deals with viruses, which are too small to strain, using chemistry, UV light or a much finer element. Most backcountry hiking needs a filter; international travel often needs a purifier.
Soft flask: A soft flask is a collapsible bottle, usually 250 to 750 ml, carried in the front pockets of a hydration vest. It shrinks as you drink so it doesn't slosh, and you can see exactly how much water you have left.
Hydration bladder: A hydration bladder is a flat water reservoir carried inside a pack with a drinking hose routed over the shoulder. It holds 1.5 to 3 liters, packs flat against your back and lets you drink without stopping or taking the pack off.
Bite valve: A bite valve is the silicone mouthpiece on the end of a hydration reservoir's drink tube. It stays shut until your teeth compress a slit in it, then self-seals when you let go, so water only flows while you are drinking.
Quick disconnect: A quick disconnect is the two-part coupling in a hydration hose that lets you unclip the tube from the reservoir without threading it back through your pack. Both halves usually self-seal, so you can pull the bag out to refill and neither end drips.
Hard-anodized aluminum: Hard-anodized aluminum is aluminum whose surface has been grown into a thick, very hard oxide layer by an electrochemical bath. In cookware it gives a pot that spreads heat far more evenly than titanium and resists scratching far better than bare aluminum.

Trekking poles

Lever lock: A lever lock clamps a pole's telescoping sections with an external cam lever you flip closed. It holds under load better than a twist lock, works with cold or gloved hands, and can be tightened with a small screw when it starts slipping.
Twist lock: A twist lock adjusts a pole by rotating one section against another, which expands a plastic plug inside to grip the shaft. It's lighter and cleaner than a lever lock and much more prone to slipping once it wears or gets dirty.
Z-pole: A Z-pole folds into three or four short sections joined by an internal cord, like a tent pole, instead of telescoping. It packs down to around 13 to 16 inches, which is short enough to stow in a running vest or strap flat to a small pack.
Carbide tip: A carbide tip is the hard tungsten carbide point at the end of a trekking pole. It bites into rock, ice and packed dirt where a steel or rubber tip would skate, and it stays sharp for years of use.
Basket: A basket is the disc near the tip of a trekking pole that stops it sinking too far into soft ground. Small trekking baskets suit dirt and mud; wide snow baskets keep the pole from disappearing into powder.
Choke-up grip: A choke-up grip is the strip of foam running down the shaft below the main handle. On a steep climb you slide your hand down onto it, effectively shortening the pole for a few steps without stopping to adjust the length.
Anti-shock: Anti-shock is an internal spring in a trekking pole that compresses slightly on each plant to soften the impact. It adds weight and complexity, most experienced hikers switch it off or buy poles without it, and some people with joint pain like it.

Lighting and electronics

Lumens: Lumens measure the total light a headlamp emits in all directions. It's the headline number on every box and it says nothing about where that light goes, so a 400 lumen lamp with a bad beam can be less useful than a 200 lumen one with a good one.
Beam distance: Beam distance is how far a headlamp usefully projects light, quoted in meters. The industry standard measures it to the point where illumination falls to 0.25 lux, roughly the brightness of a full moon, which is dimmer than most people picture.
Flood vs spot beam: A flood beam spreads light wide and close for camp tasks and slow ground. A spot beam concentrates it into a narrow cone that reaches further, for seeing ahead at speed. Most trail headlamps mix both, and the mix matters more than the lumen count.
Regulated output: A regulated headlamp holds a steady brightness as its battery drains, then drops off sharply near the end. An unregulated one fades continuously from the moment you switch it on, so it's dim long before the battery is actually empty.
Reactive lighting: Reactive lighting uses a sensor to measure reflected light and adjusts brightness automatically, dimming when you look at a map and brightening when you look down the trail. It extends battery life and can feel unpredictable at speed.
IP rating: An IP rating states how well a device resists solids and water, under the IEC 60529 standard. The first digit covers dust and the second water, so IPX4 is splash resistant, IPX7 survives brief submersion, and IP67 does both.
GPX file: A GPX file is the standard open format for storing GPS routes, tracks and waypoints as plain text. It's what you download from a trail site and load onto a watch or phone, and almost every mapping app and GPS device reads it.
Breadcrumb navigation: Breadcrumb navigation draws your loaded route as a line on a blank screen with an arrow for your position, without any underlying map. It tells you whether you're on the route, and nothing about what's around you.
ABC sensor: ABC stands for altimeter, barometer and compass, the three sensors in an outdoor watch. The altimeter and barometer are the same pressure sensor read two ways, and the compass is a magnetometer that gives you a heading when you're standing still.

Bears and food storage

Bear canister: A bear canister is a rigid container with a lid a bear can't open, used to store food and scented items overnight. Many parks and wilderness areas require an approved model, and where they do it's a regulation rather than a recommendation.
IGBC certification: IGBC certification is the Interagency Grizzly Bear Committee's testing programme for bear-resistant products. Containers are tested against live captive grizzlies and by mechanical means, and passing earns a certification number many land managers reference.
SIBBG: SIBBG is the Sierra Interagency Black Bear Group, which coordinates black bear management across Yosemite, Sequoia and Kings Canyon, Inyo National Forest and neighbouring lands. It maintains the allowed food-storage container list used across much of the Sierra Nevada.
Bear-resistant: Bear-resistant is the accurate term for certified food storage: the container holds up against a determined bear for a defined test period. Bear-proof is marketing. Given enough time and motivation, a bear can defeat almost anything.
Ursack: An Ursack is a soft, flexible bear bag made from cut-resistant fabric that ties to a tree instead of being a rigid container. It's much lighter and more packable than a canister, and it isn't accepted everywhere canisters are required.

Navigation and safety

Satellite messenger: A satellite messenger is a handheld device that sends text messages and an SOS through a satellite network rather than a cell tower, so it works where there is no phone signal. Most need a paid subscription to do anything at all.
Leave No Trace: Leave No Trace is a set of seven principles for using the outdoors without degrading it, published by a nonprofit of the same name and adopted by most US land managers. It covers waste, camping, fire, wildlife and how you treat other people.
Cat hole: A cat hole is a small pit dug to bury human waste in the backcountry, the standard being 6 to 8 inches deep and at least 200 feet from water, trails and camp. In many popular areas it is no longer permitted and waste must be packed out.
Switchback: A switchback is a sharp reversing turn in a trail that climbs a slope in a zigzag instead of straight up. It trades distance for a manageable gradient, and cutting the corner between two of them is the single most damaging thing a hiker routinely does.
Cairn: A cairn is a stack of rocks built to mark a route where paint blazes and a visible tread will not work, typically above treeline or across slabs. Official cairns are placed by land managers, and building your own is discouraged almost everywhere.
Blaze: A blaze is a painted mark or fixed tag on a tree, post or rock that confirms you are on a particular trail. The color identifies the route, and a doubled blaze is a standard warning that the trail is about to turn or something else has changed.
Scree: Scree is a slope of small loose rock, roughly gravel to fist sized, that shifts under your weight as you walk on it. It is exhausting to climb, fast and hard on the knees to descend, and it destroys footwear faster than any other common surface.
Talus: Talus is a slope of large loose blocks, from roughly dinner-plate to car sized, that you cross by stepping from one rock to the next. The hazard is not sliding but a block that rocks or shifts under your weight, which is how ankles and legs get trapped.
Yosemite Decimal System: The Yosemite Decimal System rates how technical terrain is on a scale from class 1 to class 5. Class 1 is walking, class 2 adds rough ground and occasional hand use, class 3 is scrambling where a fall could injure you, class 4 is exposed scrambling, and class 5 is roped climbing.

Trail terms

Base weight: Base weight is everything in your pack except food, water and fuel: the gear that doesn't get used up. It's the number backpackers compare, because consumables vary with trip length while base weight is a property of your kit.
Ultralight: Ultralight is a style of backpacking built around a base weight under 10 lb. It gets there by making the big three lighter and by carrying fewer things, which trades comfort in camp and margin in bad conditions for comfort while walking.
Fastpacking: Fastpacking is covering a multi-day route with a pack light enough to run in, somewhere between trail running and ultralight backpacking. Typical loads run 8 to 20 liters, and the trip is usually run downhill and on the flat and hiked uphill.
Thru-hiking: Thru-hiking is walking a long trail end to end in one continuous trip, usually within a single season. The Appalachian Trail, Pacific Crest Trail and Continental Divide Trail are the best-known examples in the US, each taking several months.
Shoulder season: The shoulder seasons are spring and autumn, the months either side of settled summer conditions. Days can be warm and nights near freezing, weather changes faster, and gear that works in July is often not enough in late September.
Three-season: Three-season gear is built for spring, summer and autumn but not sustained winter conditions. It's the default rating for most backpacking equipment, and in practice it means handling rain, wind and light frost but not deep snow.
Layering system: A layering system is the practice of combining a moisture-moving base layer, an insulating mid layer and a protective shell, so you can regulate temperature by adding and removing pieces rather than relying on one heavy garment.
Zero day: A zero day is a day on a long trail where you walk no trail miles at all, usually taken in a town to rest, resupply and deal with logistics. A nero is a near-zero: a handful of miles into or out of town with the rest of the day off.
Cowboy camping: Cowboy camping is sleeping outside with no shelter over you: a pad, a bag or quilt, and the sky. It saves the weight and the time of pitching a tent, and it trades away protection from rain, wind, dew, insects and anything that walks past in the night.
Postholing: Postholing is breaking through soft snow with each step and sinking to your shin, knee or thigh, leaving a line of holes behind you. It is exhausting, it can drop your pace to under a mile an hour, and it damages the trail for everyone following.
Slickrock: Slickrock is bare, exposed sandstone with no soil on it and no tread cut into it. You walk on the rock itself and follow cairns rather than a path. Dry sandstone gives excellent grip; wet or dusty sandstone gives very little, which is where the name misleads people.

All terms, A to Z

#A B C D E F G H I L M O P Q R S T U V W Y Z