Sure thing, the first number (5) is the class of climb. A sidewalk would be 1; rock climbing begins (and ends) at 5. The second number reflects the difficulty

Sure thing, the first number (5) is the class of climb. A sidewalk would be 1; rock climbing begins (and ends) at 5. The second number reflects the difficulty of the [hardest part of the] climb. I believe it originally went from 1-10, with 10 being the hardest thing a human could climb, but innovations in climbing shoes and better climbers have raised the max over the years, so now it goes from 1-15. Imagine the scale as being of exponential difficulty. For the same climber who spent a week going from 5.5 to 5.6, it may take a year to go from 5.10 to 5.11. So you can imagine how elite a 5.14 climber is, let alone a 5.15 one. http://en.wikipedia.org/wiki/Grade_%28climbing%29#Free_climbing_2 http://en.wikipedia.org/wiki/Grade_%28climbing%29#Free_climb...