For the gym, it’s all about mobility, breathability, and personal style. Stretchy yoga pants or athletic tights are always a good option, but make sure they’re not see-through when you bend over. If you go with pants, opt for a looser fit but not too long and not too baggy. You want room to move, but not so much material that it gets bunched up under a harness or caught around your feet and ankles. Go with a light, breathable fabric, nothing heavy like denim or canvas. Many climbers prefer shorts in the gym year-round because it’s almost always hot and humid in there, so the more air flow, the better. If you go with shorts, follow the same rule as pants: looser fit but not too baggy. Basketball shorts and short running shorts are often uncomfortable and bunchy under a harness. For a top you can wear almost anything that lets you move your arms: athletic tank tops and regular-fitting T-shirts are perfectly suitable.
When a boulderer falls, she lands on a thick foam mat that absorbs the impact. These are usually permanently installed by the gym. (If your gym has movable crashpads, make sure to get proper instruction on where to place them.) “Spotters” are other climbers who can help you land safely on the pads. Make sure to learn safe spotting technique before attempting it yourself, and learning safe falling habits are important too. The climbs in bouldering are called “problems,” because often they require complex movement patterns to “solve” them and get to the top. Problems are usually graded using the V-scale, with VB or V0 being the easiest, and higher numbers being harder. Many gyms will set problems up to V13. (The hardest outdoor boulder problems are suggested at a grade of V17.) Some gyms will use their own grading systems with dots or colors, but they usually all correspond to the V-scale. A gym’s bouldering area has shorter walls, and might have some spots you can top out, meaning the climb ends when you’re standing on top.
The climber, belayer, and the entire rope start on the ground at the base of the climb. The climber ties into one end of the rope, and the belayer clips in several feet down the rope from the climber. As the climber moves up the wall, he clips the rope into preplaced bolts, which minimize the distance he can fall. The belayer feeds out rope through the belay device as the climber goes up, always ready to catch a fall. Once the climber is done, the belayer lowers him to the ground. For both toproping and lead climbing, the climbs are called “routes,” and routes are rated by the Yosemite Decimal System (YDS). Climbs will be graded from 5.0 (easiest) to 5.14 (hardest). (The hardest outdoor sport climb in the world is 5.15d.) Sometimes the number will have a letter (a, b, c, or d) or a plus (+) or minus (-) sign after it, like 5.11a or 5.11-, which is easier than 5.11b and 5.11+. If an area of the climbing wall does not have any topropes already hanging, that means it’s for lead climbing only.