Editing Yosemite Decimal System (section)

==Description==
[[File:Knife Edge of Capitol Peak.jpg|thumb|right|upright=1.25|The Knife Edge on [[Capitol Peak (Colorado)|Capitol Peak]] in Colorado is an example of a Class 4 climb]]
The class 5 portion of the class scale is primarily a [[rock climbing]] classification system, while classes 1–4 are used for [[hiking]] and [[scrambling]].<ref name=FoHGrading/> The current definition for each class is:<ref name=FoHGrading>{{cite book|title = Mountaineering: The Freedom of the Hills|year = 1997|edition = 6th|publisher = [[The Mountaineers (Pacific NW)|The Mountaineers]]|location = Seattle|isbn = 0-89886-426-7|pages=511–514}}</ref>
; Class 1:[[Hiking]] or [[trail running|running]] on a [[trail]]. 
; Class 2:Simple [[scrambling]], with the possibility of occasional use of the hands.
; Class 3: Scrambling. A rope could be carried. 
; Class 4: Simple [[climbing]], possibly with [[exposure (heights)|exposure]]. A rope is often used. Falls could be fatal. Natural [[protection (climbing)|protection]] can easily be found.
; Class 5: It is considered technical roped [[free climbing]]; [[belaying]] is used for safety. Un-roped falls can result in severe injury or death.
The American YDS system is the dominant system in North America, and it and the French numerical system are the most dominant systems worldwide; beyond the easiest grades, they can be [[#Comparison tables|exactly aligned]].<ref name=CAI>{{cite web| first1=G |last1=Mandelli |first2=A |last2=Angriman | date=2016 | title=Scales of Difficulty in Climbing | publisher=Central School of Mountaineering, [[Club Alpino Italiano]], Italy | url=https://www.theuiaa.org/documents/sport/THE-SCALES-OF-DIFFICULTY-IN-CLIMBING_p1b.pdf | accessdate=17 February 2025}}</ref><ref name=Rockfax/> The exact definition of the classes is somewhat controversial,<ref>{{cite web
  | url = http://climber.org/data/decimal.html
  | title = The Yosemite Decimal System
  | publisher = Climber.org
  | access-date = 2009-01-15}}</ref> and updated versions of these classifications have been proposed.<ref>{{cite news
  | last = Rose
  | first = Jeff
  | title = Terrain Classification, Climbing Exposure, and Technical Management
  | publisher = Journal of Outdoor Recreation, Education, and Leadership
  | pages = 242–257
  | url = http://digitalcommons.wku.edu/jorel/vol5/iss3/6/ }}</ref>

Climbers use class "5" as a prefix, which is then followed by a [[Full stop|period]] (originally a [[decimal point]]) and a number that starts at 1 and counts up with increasing difficulty (e.g. 5.4, 5.5, 5.6, etc.).<ref name=Rockfax/> At  5.10, the system adds the letters "a", "b", "c", and "d" as further refinements between levels, and the scale continues upward (e.g. 5.10a, 5.10b, 5.10c, 5.10d, 5.11a, 5.11b, etc.).<ref name=FoHGrading/><ref name=Rockfax/>

The American YDS system is an open-ended scale, with the current hardest climb being 5.15d, established by ''[[Silence (climb)|Silence]]'' in 2017. Like the French system, the numerical component of the American YDS system is focused on the hardest move on the route.<ref name=FoHGrading/>