The vocabulary of the mountains.

Ski & snowboard difficulty ratings

North American resorts rate every run using the same four-symbol system, shown as a shape on trail maps and on every run listed on PeakSeeker:

The one thing to know: these ratings are relative, not absolute. A blue run at a small local hill can be steeper than a blue run at a massive resort — each resort rates its own terrain against its own easiest and hardest runs, not against a universal scale. A green at one resort and a green at another aren't guaranteed to be the same difficulty. Always check trail conditions and your own comfort level, not just the color.

Outside North America, most European resorts use a similar four-color system — green, blue, red, black — where red sits in roughly the same difficulty band as North American black, and black is reserved for the most extreme groomed or off-piste terrain. If a resort on PeakSeeker uses the European scale, the color shown reflects that resort's own system.

Terrain parks and progression areas are usually rated on their own separate scale — often green/blue/black same as runs, sometimes a distinct "small/medium/large" or "beginner/intermediate/advanced" park label — because a park's difficulty is about the size and consequence of the features (jumps, rails, boxes) it contains, not slope angle. Never assume a green-rated park is beginner-friendly in the way a green run is; check feature size, not just the color.

Hiking, scrambling, and climbing — what's the difference

These three categories blur together in casual conversation but describe genuinely different activities, different gear, and different risk. PeakSeeker classifies every summit route into one of these (plus ski mountaineering, below), using the same system climbers and guidebooks use: the Yosemite Decimal System (YDS) class rating.

• Class 1 — Hiking. Trail or off-trail walking. Hands stay in your pockets. This covers the overwhelming majority of hiking trails.
• Class 2 — Simple scrambling. Rougher terrain — loose rock, steeper slopes — where you might use a hand for balance occasionally, but you're still walking, not climbing.
• Class 3 — Scrambling. You're using your hands regularly to move upward, and exposure (the consequence of a fall) starts to matter. Most people don't rope up for Class 3, but a fall could genuinely hurt you.
• Class 4 — Steep scrambling / easy climbing. Simple climbing moves on steep, exposed terrain. Many parties rope up here, especially in wet or icy conditions — a fall is likely to be serious.
• Class 5 — Technical climbing. Real rock climbing, requiring a rope, protection, and a belay. Class 5 splits into its own decimal grading system (5.0 through 5.15+ and climbing) — see Climbing Grades below.

A second, separate number often rides alongside the YDS class or grade on real alpine routes: an overall Grade, written in Roman numerals I through VII. Where YDS describes the hardest single move, the Roman-numeral Grade describes the route as a whole — its length, commitment, and how long a competent party should expect to be on it (Grade I: a few hours; Grade VI: a full day of hard climbing; Grade VII: multi-day, remote, high-altitude). A route can be technically easy (5.6) but a serious Grade V because of its length and remoteness — the two numbers answer different questions, and PeakSeeker shows both where a route's source reports both.

On PeakSeeker, a summit route's discipline badge reflects where it falls on this scale — "hike," "scramble," or "alpine climb" — based on its hardest sustained section, not its average. For what to bring at each level, see Gear & Packing Basics.

Climbing grades

Once a route crosses into Class 5 territory, difficulty is expressed with a specific grade rather than a class number. You'll see a few different systems on PeakSeeker, depending on where a route is and which reference it was sourced from:

Yosemite Decimal System (YDS) — the standard in North America. Grades run 5.0 (easiest roped climbing) to 5.15+ (the hardest routes in the world, climbed by a handful of elite climbers). A letter suffix (a/b/c/d) can further refine grades 5.10 and up — 5.10a is easier than 5.10d.

French (sport) grading — the standard across most of Europe. Grades run numerically (3, 4, 5, 6a, 6b... up to 9c+), with a letter and +/- refining each number band. Roughly: French 6a is comparable to YDS 5.10a.

UIAA grading — used in parts of the Alps and traditionally in alpine climbing, expressed in Roman numerals (III, IV, V... up to XII), sometimes with +/- refinements.

Ski mountaineering / toponeige grading — for ski descents rather than roped climbs. This system (common on European ski-mountaineering routes) combines a numeric difficulty grade with a letter exposure grade — for example, "4.2/E2" — where the number reflects technical skiing difficulty and the letter-number reflects the consequence of a fall. Some of the most serious ski descents in the world don't have a single standardized grade at all and are instead described narratively by the few people who've completed them — where that's the case, PeakSeeker shows the route's real description rather than forcing it into a number that doesn't exist.

Bouldering (V-scale / Fontainebleau) — for climbing without a rope, close enough to the ground that a crash pad and a spotter are the safety system instead of a belay. The V-scale (Vermin scale), standard in North America, runs V0 (easiest) to V17 (the hardest boulder problems climbed anywhere). The Fontainebleau ("Font") scale, standard in Europe, runs a comparable range numerically (4 to 9a) using its own numbering, distinct from French sport grades despite the visual similarity.

Ice and mixed climbing — ice routes are graded WI (water ice) 1 through 7, reflecting steepness and ice quality/reliability (WI3 is moderate, sustained ice; WI6+ is thin, vertical-to-overhanging, unreliable ice). Mixed climbing — routes combining rock and ice, climbed with crampons and ice tools on both — uses an M-scale (M1 easiest, upward past M12 at the hardest currently climbed), which is not directly comparable to either WI or YDS.

A route's page on PeakSeeker always shows the specific grade system it was sourced in, rather than silently converting between them — a French 6a and a YDS 5.10a describe very similar climbing, but they aren't identical, and guessing the conversion isn't something we do quietly.

Rough conversion reference — useful for getting a feel for a grade in a system you don't normally use. These are approximate; the further up the scale you go, the less exact any conversion gets, since national grading traditions diverge in how they weight technical difficulty vs. sustained effort.

Climbing style vocabulary

Grades describe how hard a route is; these terms describe how it's climbed:

• Top-ropeThe rope runs from the climber, up through an anchor at the top of the route, back down to a belayer on the ground. The lowest-risk way to climb roped, common for beginners.
• Lead climbingThe climber goes up first, clipping the rope into protection points as they go, with no rope above them until they place the next piece. A fall means falling past your last protection point — real consequence, and a different skill set than top-roping.
• Sport climbingLead climbing on a route with permanent bolted protection already fixed to the rock. The gear question is simple: quickdraws and a rope.
• Trad (traditional) climbingLead climbing where the climber places their own removable protection (cams, nuts) into rock features as they go, and removes it afterward, leaving no trace. Requires more gear and more judgment than sport climbing.
• Multi-pitchA route too long to climb in one rope-length, broken into consecutive pitches with belay stations in between. Common on real alpine routes, as opposed to single-pitch cliffs.
• Aid climbingMaking upward progress by pulling or stepping on placed gear directly, rather than the rock itself — used on terrain too blank or difficult to free climb.
• Free soloClimbing without a rope or any protection at all. A fall at any point is a fall with no backup. Extremely high-consequence and practiced by very few people, on very specific routes, after extensive preparation — not a beginner activity under any circumstance.
• OnsightSuccessfully climbing a route on the very first attempt, with no prior knowledge of its moves. The purest style of ascent.
• RedpointSuccessfully leading a route cleanly (no falls or rests on gear) after having practiced it on a previous attempt.
• SendGeneral climbing slang for successfully completing a route, in any style.

Route history & achievement terms

Terms you'll see in a route's history and description on summit pages:

• First ascent (FA)The first recorded successful climb of a route or summit, by any style. The climbers credited with an FA, and the date, are often the most historically documented facts about a route — and the reason PeakSeeker shows first-ascent history where it's a matter of real record, not just recent activity.
• First winter ascent (FWA)The first successful ascent completed during the calendar winter season, tracked separately from the standard-season FA because winter conditions (cold, short days, avalanche hazard, ice) can make an otherwise moderate route dramatically harder and more serious.
• Free ascent vs. aid ascentA free ascent means climbing using only the rock's natural features for upward progress, with rope and gear used purely to catch a fall, not to help move upward (see Aid climbing above, for the alternative). A route's first free ascent is often a distinct, separately notable milestone from its first ascent overall, if the original FA used aid.
• Established / "put up a route"Climbing slang for creating a new route — identifying a line up unclimbed terrain, placing any fixed protection it needs, and completing it, usually followed by documenting the route (grade, protection, description) for others.
• New routeA first ascent of a previously unclimbed line, as distinct from a repeat ascent of an established route.
• VariationA route that departs from an established line for some portion, then rejoins it — common where the original route has an avoidable hazard or a harder-than-necessary section.
• DirettissimaA route taking the most direct possible line to a summit, from the Italian for "most direct" — often steeper and more sustained than a route that seeks out the path of least resistance.
• Enchainment / link-upClimbing two or more routes or summits consecutively, in a single push, often to set or attempt a speed or style record.
• Fastest known time (FKT)An informally tracked, community-verified record for the fastest completion of a specific route, established and maintained outside of any official sanctioning body, common in trail running and fast alpine ascents.
• Solo ascentClimbing without a partner. Distinct from free solo (above) — a solo ascent can still involve a rope, self-belay techniques, or protection; it just means climbing alone rather than climbing unroped.
• Guided vs. unguidedWhether a party is climbing with a professional, certified guide (who carries real legal and safety responsibility for the party) or independently. Many of the world's most popular technical objectives are climbed guided by parties without prior technical experience in that specific discipline — a legitimate and common way to access serious terrain safely, not a lesser way to climb it.

Avalanche danger scale

Both use the same five-level North American Avalanche Danger Scale:

This scale rates the danger of the terrain, not just the weather — the same storm can produce very different ratings in different mountain ranges depending on the existing snowpack. PeakSeeker shows this rating live where it's officially published; where a resort or region has no active bulletin (commonly, outside of winter/spring avalanche season), the site says so plainly rather than showing a stale or guessed number.

Avalanche problem types

The danger rating above answers "how bad is it right now" — the problem type answers "what kind of avalanche is actually the concern today," and professional forecasts name one or more of these alongside the danger level:

• Storm slabNew snow from a recent storm that hasn't yet bonded to the snow beneath it. Usually stabilizes within a day or two of a storm ending.
• Wind slabDense, wind-deposited snow sitting on top of weaker, looser snow beneath it (see also Wind slab in the Skiing & Snow Vocabulary section below). Often invisible from the surface.
• Persistent slabA slab sitting on a weak layer (surface hoar, faceted snow) that can remain reactive for days to weeks after it forms — the most dangerous and least predictable problem type, since it doesn't heal on a storm's timeline.
• Deep persistent slabThe same mechanism as a persistent slab, but on a weak layer buried deep in the snowpack, often from earlier in the season. Rare, but produces the largest and most destructive avalanches when it does release.
• Wet slabA cohesive slab weakened by water percolating down through it, typically during spring warmup or rain-on-snow events.
• Loose dryDry snow that avalanches without cohesion, sluffing downhill in a fan shape rather than releasing as a slab. Usually smaller and less dangerous than a slab release, but can still knock a climber or skier off their feet into consequential terrain.
• Loose wetThe wet-snow equivalent of loose dry, common in spring; can trigger a larger wet slab below it as it runs.
• Cornice fallA collapsing overhanging snow cornice (see Cornice in the terrain glossary below), which can trigger a larger avalanche on the slope it lands on even if that slope was otherwise stable.
• Glide avalancheThe whole snowpack slowly slides on the ground beneath it, usually on smooth rock or grass slopes, and can release with little warning after an extended period of visible cracking ("glide cracks"). Notoriously unpredictable in timing.

Altitude, weather & conditions vocabulary

Elevation changes the weather, and the weather is a real part of trip planning, not a footnote. Terms you'll see on summit and resort pages, and worth understanding before you rely on a forecast:

• Elevation gainThe total amount of uphill climbing on a route, adding up every up-section rather than just the net difference between start and summit. A route can have a modest net elevation change but a much larger elevation gain if it rolls up and down repeatedly — always the more honest number for judging effort.
• Freezing levelThe elevation at which air temperature crosses 0°C (32°F) on a given day, reported in most mountain weather forecasts. Above it, precipitation falls as snow; below it, rain — and it can rise and fall by thousands of feet within a single storm, changing conditions dramatically over the course of a day.
• Lapse rateThe rate air temperature drops as elevation increases (roughly 3.5°F per 1,000 feet under typical conditions) — the reason a warm trailhead can mean a genuinely cold summit.
• AcclimatizationThe body's gradual physiological adjustment to reduced oxygen at altitude, which takes days, not hours. Ascending too fast for your body to acclimatize is the direct cause of altitude illness, below.
• Acute Mountain Sickness (AMS)Headache, nausea, fatigue, and poor sleep from ascending faster than your body can acclimatize, typically starting above roughly 8,000 feet. Common and usually resolves with rest or descent; the serious escalations (HAPE, fluid in the lungs, and HACE, swelling in the brain) are medical emergencies requiring immediate descent. This is general background, not medical advice — anyone heading to real altitude should get guidance from a real altitude-medicine source before they go.
• Temperature inversionA weather pattern where temperature rises with elevation instead of falling — cold, often smoggy air trapped in a valley beneath clear, warmer air above. Common in winter high-pressure systems, and the reason a summit can be sunnier and warmer than the valley below it.
• Lenticular cloudA smooth, saucer-shaped cloud that forms over and downwind of a peak in strong winds. Visually striking, but a reliable sign of high winds at altitude even on an otherwise clear day.
• Katabatic windCold, dense air draining downhill under gravity, typically overnight and into early morning, off glaciers and high snowfields. Can produce sudden, localized wind well beyond what the general forecast suggests.
• Diurnal windsThe daily up-valley/down-valley wind cycle driven by mountains heating and cooling faster than the air around them (upslope by day as sun-warmed air rises, downslope at night as it cools) — a factor in both weather planning and, on glaciated terrain, snow-bridge stability timing.
• SpindriftFine, wind-blown loose snow, distinct from falling snow — can reduce visibility and accumulate in gullies and couloirs even on a non-snowing day.

Navigation & trip-planning terms

Terms that show up in route descriptions, permit systems, and PeakSeeker's own trip-planning tools:

• WaypointA saved GPS coordinate marking a specific point — a trailhead, a junction, a water source, a bail-out point — used for navigation reference rather than following a continuous track.
• Track (GPX track)A recorded or planned line of GPS coordinates showing an actual route across terrain, as opposed to a single waypoint. Most navigation apps can record a track live or load one prepared in advance.
• BearingA compass direction, expressed in degrees (0–360°), used to travel a straight line toward a target when landmarks aren't visible (whiteout, forest, flat light).
• DeclinationThe difference between magnetic north (what a compass actually points to) and true north (what a map is drawn to). Varies by location and drifts slowly over time; ignoring it introduces real, compounding navigation error over distance.
• Contour line / contour intervalThe lines on a topographic map connecting points of equal elevation; the contour interval is the elevation difference between adjacent lines. Tightly packed lines mean steep terrain; widely spaced lines mean gentle terrain — reading contour spacing is the core skill of judging terrain steepness from a map alone.
• UTM coordinatesA grid-based coordinate system (Universal Transverse Mercator) often preferred over latitude/longitude for backcountry navigation because it measures distance in meters on a flat grid, making on-the-ground distance and direction easier to reason about than degrees of latitude/longitude.
• TrailheadThe starting point of a trail, typically where a road ends and the trail itself begins; often the reference point for permits, parking, and route mileage.
• Permit / quotaMany popular trails and summit routes limit the number of people allowed per day via a permit system, to protect the experience and the land. Where PeakSeeker knows a route requires one, it's shown on that route's page — but always confirm current requirements with the managing agency before you go, since quota systems and requirements change.
• Timed entryA permit variant that assigns a specific arrival window rather than just a daily cap, increasingly common at high-traffic trailheads and parks.
• Egress / bail-out pointA planned point along a route where a party can turn back or exit to a safer, faster way down if conditions, weather, or time force a change of plan. Identifying these before you start, not mid-route, is a core piece of trip planning.
• Turnaround timeA decided time, set before starting, by which the party turns back regardless of how close they are to the objective — the single most effective tool for avoiding summit-fever decisions made after judgment has already started to erode from fatigue or urgency.

General mountain terrain glossary

Terms you'll run into on resort and summit pages that aren't everyday vocabulary:

• ProminenceHow much a peak rises above the surrounding terrain, measured from its summit down to the highest connecting ridge to any higher peak. A useful way to tell a genuine, standalone mountain from a bump on the shoulder of a bigger one — a peak can be very tall in elevation but low in prominence if it's just part of a larger massif.
• Vertical dropThe elevation difference between a resort's highest and lowest lift-served points. The standard way ski resorts compare terrain size.
• Skiable areaThe total terrain a resort has open to skiers and riders, usually measured in acres or hectares.
• Col / saddleA low point on a ridge between two peaks, often the natural walking or climbing route between them.
• CouloirA steep, narrow gully or channel on a mountainside, often snow- or ice-filled — a common route for both climbers and ski mountaineers.
• ArêteA sharp, narrow ridge, often formed between two glacial valleys.
• CirqueA bowl-shaped hollow carved into a mountainside by glacial erosion, often at the head of a valley.
• CorniceAn overhanging ledge of wind-deposited snow on a ridge, which can collapse without warning — a real avalanche and fall hazard.
• MoraineA ridge or mound of rock and debris deposited by a glacier, either at its edges (lateral moraine) or its farthest point of advance (terminal moraine).
• TreelineThe elevation above which trees stop growing. Terrain above treeline is more exposed to wind, weather, and avalanche hazard, with no vegetation to anchor snowpack.
• ExposureIn climbing and scrambling, how serious the consequences of a fall would be, independent of how technically hard the move is. A move can be easy but highly exposed (a long fall if you slip) or hard but not exposed (a fall onto a ledge two feet down).
• Scree / talusLoose rock covering a slope. Scree is smaller/finer, talus is larger broken rock — both are unstable underfoot and a common source of slips and rockfall.
• Alpine startBeginning a climb or ascent well before dawn, typically to cross hazardous terrain (glaciers, snow slopes prone to afternoon softening, or exposed ridgelines) while conditions are still firm and cold, and to be off the summit before afternoon weather builds.
• CruxThe single hardest move or section of a climbing route.
• PitchOne rope-length section of a roped climb, typically 30–60 meters, climbed between two belay points.
• BelayThe system of managing rope to catch a climbing partner's fall; also used as a verb ("belaying").
• Rappel / abseilDescending a rope under control using friction, typically to get down terrain too steep or exposed to downclimb safely.
• Glacier travelMoving across a glacier, which introduces hazards (hidden crevasses under snow bridges) not present on normal terrain — typically done roped to a partner and with crevasse-rescue skills.
• AspectThe compass direction a slope faces (north-facing, south-facing, etc.). One of the most important factors in avalanche and snow-condition assessment, since sun and wind exposure differ enormously by aspect — a north-facing slope can hold unstable snow long after a south-facing one has stabilized.
• MassifA large, connected block of mountains or a compact group of peaks, treated geologically as one unit even though it contains multiple named summits.
• BasecampA semi-permanent camp established below a mountain's technical terrain, used as a staging point for summit attempts above it.
• SwitchbackA zigzagging trail or route pattern used to gain elevation at a manageable grade on steep terrain, rather than climbing straight up the fall line.
• BergschrundA crevasse-like gap that forms where a glacier's moving ice pulls away from the stagnant snow/ice clinging to the steep rock above it, common at the top of glaciated climbing routes and often the technical crux of getting onto a peak's upper slopes.
• SeracA block or tower of glacial ice, formed where a glacier fractures over uneven or steep ground. Unstable and capable of collapsing without warning — a real objective hazard on routes that pass beneath or through icefall terrain.
• GendarmeA rock pinnacle or tower interrupting an otherwise walkable ridgeline, usually requiring a short technical move or a detour to pass.
• False summitA high point that looks like the top from below or from a distance, but isn't — the true summit lies farther on, often hidden by the terrain in between. A common source of "just a bit further" fatigue on long routes.
• HeadwallA steep slope or rock face at the head of a valley or cirque, often the technical crux guarding access to a summit ridge above it.
• Knife-edge ridgeA ridge narrow enough that both sides drop away steeply, sometimes requiring careful balance or a straddle-and-shuffle technique to cross.
• RunoutThe terrain a fall, slide, or avalanche travels through and comes to rest in; also used to describe a climbing route with long gaps between protection ("a runout section").
• TarnA small mountain lake, typically formed in a glacially-carved basin.
• DrainageA valley or watercourse that channels runoff downhill; often used as a natural navigation reference ("follow the drainage down").

Skiing & snow vocabulary

Terms beyond the difficulty ratings above that show up around resort conditions, backcountry travel, and snow itself:

• Fall lineThe natural downhill direction gravity would pull you on any given slope — the most direct line down. Skiing "the fall line" means skiing that direct line rather than traversing across it.
• GroomerA run that's been mechanically flattened and smoothed overnight by grooming equipment, producing a firm, consistent surface — the opposite of ungroomed powder or bump terrain.
• PowderFresh, unpacked, unskied snow. The condition most resort skiers chase after a storm.
• Corn snowA springtime snow condition where repeated freeze-thaw cycles turn the surface into loose, granular crystals — soft and forgiving when timed right (typically mid-morning, once the overnight freeze has just started to soften), unpleasant when the timing's off.
• Moguls (bumps)A field of rounded snow mounds formed on a slope by repeated skier turns, usually on steeper terrain. Requires a distinct technique from groomed-run skiing.
• Tree skiing (glades)Skiing through forested terrain rather than open, cleared runs. Often holds powder longer than open slopes, at the cost of needing to navigate around trees.
• SidecountryTerrain accessible from a resort's lifts but outside the resort's patrolled, avalanche-controlled boundary. It looks like an extension of the resort but carries full backcountry risk — no avalanche mitigation, no patrol response. A common source of accidents specifically because it doesn't feel remote.
• BackcountryUngroomed, unpatrolled terrain reached under your own power (skinning, hiking, snowmobile, helicopter), entirely outside any resort's avalanche mitigation or rescue infrastructure.
• Ski touring / skinningTraveling uphill on skis fitted with "skins" (traction strips that grip snow going forward but slide going back), used to access backcountry terrain without a lift. The skins are removed for the descent.
• Skin trackThe established uphill path set by ski tourers, usually switchbacking up a slope at a sustainable, consistent grade.
• WhiteoutA weather condition where snow, fog, or cloud eliminates visual contrast and depth perception, making it difficult or impossible to distinguish terrain features, horizon, or even up from down. A serious navigation and safety hazard both in-bounds and in the backcountry.
• Wind slabA dense, cohesive layer of snow deposited by wind, often sitting on top of weaker, looser snow beneath it. One of the most common and dangerous avalanche problem types, because it can look and feel stable right up until it isn't.
• CorduroyThe ridged texture left on a run by grooming equipment overnight; skiing "corduroy" means skiing freshly groomed terrain, usually early in the day before it's tracked out.
• HardpackA firm, dense snow surface, either from grooming, wind, or a freeze — the opposite of soft powder, and a different (often more demanding) surface to ski or ride well on.
• BoilerplateAn extreme, icy version of hardpack, usually from rain-then-freeze or repeated freeze-thaw without fresh snow — hard enough that edges (not skill alone) become the deciding factor in control.
• Base depthThe accumulated snow depth at a resort's base area, a standard reported metric alongside recent snowfall for judging season conditions.
• SluffA small, fast-moving loose-snow slide triggered by a skier's turns on steep terrain, distinct from a full avalanche release but still capable of knocking someone off balance in consequential terrain.
• Face shotDeep enough powder that a turn throws snow up into the rider's face — informal but universally understood shorthand for genuinely deep conditions.

Not sure what to actually bring? See Gear & Packing Basics.