Bouldering is a lot like free climbing in that climbers do not use ropes, hooks or aids of any sort -- just their hands and feet and a little bit of ingenuity. The main difference between the two is that bouldering usually takes place closer to the ground, where a fall would not be as dangerous, while free climbing can be at any height. The name "bouldering" comes from the fact that close to the ground there tend to be a greater amount of large rocks and boulders to climb.
The two most common systems for rating bouldering are the V grade and the Fontainebleau grade. Another less frequently used scale is the B grade.
The V grade system was developed in the U.S. by a climber named John Sherman. He was nicknamed "Verm" by his friends; hence the "V." The V grades attempt to rate the overall climb. Originally, the V grades went from V0 to V15 (V0 being the easiest and V15 being the hardest), but the V grade was criticized for not including enough easier ratings. And so grades of V0+ and V0- were added, as well as VB (Beginner), to account for easier climbs.
Because of the problems with the V grade system, the B grade system was developed. It ranges from B0 to B15 and is meant to allow more room in the lower grades (both B0 and B1 cover what the V scale describes as V0).
Another popular bouldering grade system is the Fontainebleau system. Developed around the climbing scene in Fontainebleau, France -- which some call the bouldering capital of the world -- this system uses as series of numbers, letters, and symbols to rate a climb. The scale ranges from 1 to 8, where higher numbers indicate greater difficulty. Each number is further divided with letters a, b and c, and the use of a + symbol. So, for example, each number would follow a sequence like this: 6a, 6a+, 6b, 6b+, 6c, 6c+ and so on.
Bouldering and free climbing are all about using your body to get around the rocks. But sometimes it can be too difficult -- or too dangerous -- to attempt a climb without the use of tools and climbing aids. In the next section, we'll talk about the grading scales for aid climbing, or climbing with climbing tools, which are used for some of the world's most daring and dangerous climbs.