At a ski resort, you have the option of going down different runs that are associated with different skill levels. Green circle is the easiest ski run for beginners, blue square is for intermediate skiers who are more comfortable with skiing, and a black diamond run (or double black) is for advanced skiers who want a challenging course.
At Mountain Reservations , They define skiers in these categories of green, blue, and black sign based on their capability, skills, and challenge level. In a poll, They asked ski questions about the last ski season 2011-2012 to compile information regarding what the ski category defines.
Via:- Mountain Reservations
