NCCS grades are often called the “Commitment Grade”; they primarily indicate the time investment in a route for an “average” climbing team.
Grade I: Less than half a day for the technical portion.
Grade II: Half a day for the technical portion.

Grade III: Most of a day for the technical portion.
Grade IV: A full day of technical climbing, generally at least 5.7. Grade V: Typically requires an overnight on the route.
Grade VI: Two or more days of hard technical climbing.
Grade VII: Remote big walls climbed in alpine style.

The overall seriousness of the complete route based on all factors of the ascent, descent, and final approach. This system is increasingly being used worldwide, including in the Americas.
F: “Facile” (easy); rock scrambling or easy snow slopes, some glacier travel, often climbed ropeless.
PD: “Peu Difficile” (a little difficult); some technical climbing and more complicated glaciers.

AD: “Assez Difficile” (fairly hard); steep climbing or long snow/ice slopes above 50o; for experienced alpine climbers only.
D: “Difficile” (difficult); sustained hard rock and/or ice/snow; fairly serious.
TD: “Très Difficile” (very difficult); long and serious.

ED1, ED2, ED3: “Extremement Difficile” (extremely difficult); the most serious climbs with the most continuous difficulties.

An overall grade reflecting the remote, cold, stormy nature of Alaskan climbing. Grade 1: Easy glacier route.
Grade 2: Not technical, but exposed to knife-edged ridges, weather, and high-altitude. Grade 3: Moderate to hard, including some technical climbing.

Grade 4: Hard to difficult, with technical climbing.
Grade 5: Difficult, with sustained climbing, high commitment, and few bivouac sites.
Grade 6: Sustained hard climbing over several thousand vertical feet requiring high commitment.

The overall grade factors in UIAA technical ratings (the Roman numerals). 1B: Some easy roped climbing.
2A: Several pitches of easy roped climbing.
2B: Some II+ and III climbing on a multi-pitch route.

3A: Contains 1-1.5 pitches of III climbing on a multi-pitch route. 3B: One or two pitches of III+/IV climbing on a full-day route. 4A: A full day route with IV+ climbing.
4B: Several pitches of IV+ or some V+ climbing.

5A: Contains several pitches of V climbing on a 1- to 3-day route. 5B: Two-plus days with some VI climbing.
6A and 6B: Multi-day routes with considerable VI or harder climbing.

In general, older routes, routes with little aid, and those put-up by climbers without extensive big-wall experience use the original aid rating system. Newer routes put-up by big-wall aficionados often are given a “New Wave” aid rating using the same symbols with new definitions. When the letter “C” replaces “A,” the rating refers to “clean” climbing—i.e., without a hammer.
Original Aid Rating System:
A0: Occasional aid moves often done without aiders (etriers) or climbed on fixed gear; sometimes called “French free.”
A1: All placements are solid and easy.
A2: Good placements, but sometimes tricky to find.

These apply to ice and mixed conditions and are used primarily by climbers familiar with Scottish conditions.
Grade I: Snow gullies and easy ridges.
Grade II: Steep snow where two ice tools may be required but technical difficulties are short. Grade III: More sustained than Grade II. Mixed ascents of moderate rock routes.

Grade IV: Steep ice with short vertical steps or long pitches up to 70o, or mixed routes requiring advanced techniques.
Grade V: Sustained ice to 80o or mixed climbs with linked hard moves.
Grade VI: Vertical ice and highly technical mixed routes.

Grade VII: Multi-pitch routes with long sections of vertical or thin ice, or mixed routes with lots of highly technical climbing.
Grade VIII and above: The hardest routes in Scotland.

This combines length, hazard, and overall challenges.
Grade I: Short, easy, and with no alpine hazards.
Grade II: One or two pitches near the car with few alpine hazards.
Grade III: Requires most of a day including the approach, which may require winter travel skills (possible avalanche terrain, placing descent anchors).
Grade IV: A multipitch route at higher altitude or remote location. Multi-hour approaches in serious alpine terrain.
Grade V: A full-day climb in alpine terrain with a long approach, long technical descent, and objective dangers.
Grade VI: A long waterfall with the character of an alpine route; usually requires at least a day to complete. Significant alpine objective hazards.
Grade VII: Longer and harder than Grade VI, with considerable dangers even to expert climbers.

These routes require considerable dry tooling (modern ice tools used on bare rock) and are climbed in crampons; actual ice is optional but some ice is usually involved.
M1-3: Easy.
M4: Slabby to vertical with some technical dry tooling.

M5: Sections of sustained vertical dry tooling.
M6: Vertical to overhanging with difficult dry tooling.
M7: Overhanging with powerful and technical dry tooling.
M8: Some roofs (nearly flat overhangs) requiring very powerful and technical dry tooling. M9-12 and above: Longer and longer stretches of horizontal roof, with increasingly tenuous tool placements and/or increasingly long and powerful moves.

Ice climbing ratings are highly variable by region and are still evolving. The following descriptions approximate the average systems, at least as used by North Americans. The WI acronym implies seasonal ice; AI is often substituted for year-around Alpine Ice and may be easier than a WI grade with the same number. Canadians often drop the WI symbol and hyphenate the technical grade with the commitment grade’s Roman numeral (ex.: II-5).
WI 1: Low angle ice you can walk on.
WI 2: Consistent 60o ice with possible bulges; good protection.
WI 3: Sustained 70o with possible long bulges of 80o-90o; reasonable rests and good stances for placing screws.
WI 4: Multiple pitches of continuous 80o ice, or a single pitch containing fairly long sections of 90o ice broken up by occasional rests.
WI 5: Long and strenuous, with a ropelength of 85o-90o ice offering few good rests; or a shorter pitch of thin or bad ice with reasonable protection that’s difficult to place.
WI 6: A full ropelength of near-90o ice, or a shorter pitch even more tenuous than WI 5. Highly technical and very scary.
WI 7: As above, but on thin poorly bonded ice or long, overhanging poorly adhered columns. Protection is impossible or very difficult to place and of dubious quality.
WI 8: Coming soon.

Snow is often described by its steepest angle (ex.: 70o) or by a range approximating its steepest angle (ex.: 70o-80o).