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Yosemite Decimal System
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<p>The Yosemite Decimal System (YDS) is a five-part <a href="/facts/Grade_(climbing)/1lMDzC54">grading system</a> used for rating the difficulty of <a href="/facts/Rock_climbing/wd5WnGnG">rock climbing</a> <a href="/facts/Climbing_routes/KqNt0Vy0">routes</a> in the <a href="/facts/United_States/P0sCdLe5">United States</a> and <a href="/facts/Canada/D5P9yqs6">Canada</a>. It was first devised by members of the <a href="/facts/Sierra_Club/BGbcjkD8">Sierra Club</a> in <a href="/facts/Southern_California/1CaAWjd2">Southern California</a> in the 1950s as a refinement of earlier systems from the 1930s, and quickly spread throughout North America. </p>