The style of bouldering is unique to the sport of rock climbing. The routes are typically short and require high strength, vs endurance as in lead or top roping. The routes are interesting, dynamic and powerful, and do not require ropes or a harness or belay partner. Due to the lack of traditional protection, the height of routes is in the range of 12' or 4m. Many climbers prefer this to any other form of the sport. Now, almost all indoor walls and gyms offer a bouldering cave or dedicated area within the gym. Bouldering has evolved and matured into its own style and category of the sport.
Bouldering requires the least amount of climbing gear.
Climbing Holds. If you build your own climbing wall you can boulder whenever you want. Climbing holds are a significant cost, but the good news if you keep your eyes open you can find great deals on line. They come in all shapes and sized ready to fasten to the wall. Furthermore it is not difficult to make your own wooden holds as described and demonstrated in the book Building Your Own Climbing Wall.
Climbing Shoes. Slip on shoes are made by many gear manufacturers to easily get on and off your feet. They are made to tight and form fit to your foot. Typically they use elastic and Velcro to fasten. Many prefer the slip on style due to the nature of the routes being low and solo and can quickly approached and tried. These shoes are usually a little lighter usually have a type of toe that is asymmetrical. The soles are typically flex type. This gives improved performance for difficult problems.
Bouldering Chalk Bag. The nature of bouldering routes demand the best possible grip and friction against the hold. Chalk (MgCO3) greatly improves traction. Bags are specifically made for groups of boulderers. Community bags allow groups to take turns on the wall and chalkup before getting up on the route. Unlike smaller chalk bags, bouldering bags aren't worn--they sit on the ground. This approach works especially well for because if worn, they tend to spill during a fall. The community type that are left on the floor also do not restrict movement, nor do they add that small amount of weight while attempting extremely difficult sequences. The large broad bottom gives them stability and allows them to stay upright even if kicked.
Crash Pads. Used to break the fall. Pads are placed under the route and help break the fall. Bouldering is considered an extreme sport so with it there is the elevated danger of injury. Bouldering pads protect from injury when falling uneven surface and twisting ankles, spraining wrists or worse. The bouldering pad should not take the place of a spotter, they provide additional protection. They are highly valuable when used at the outdoor crag, and need to be both transportable and durable.
Bouldering Routes have specific and particular attributes: The are high strength, short, and require very specific sequence. For the more difficult bouldering problems, if you don't start out with the correct hand into a sequence it is likely you won't be able to send it. Any of the climbers involved in bouldering can participate in routesetting, and that's a big factor that makes bouldering so much fun. Problems often feature steep or negative (overhanging) incline and maximize upper body and grip strength.
The Spotter. Even though climbing ropes and a Belay Device are not used, there is still the need for a partner. The spotter has a very important role. He positions himself directly under the climber and holds his arms up ready in an instant to break the fall. This is not so much "catching" as it is guiding the person to the bouldering pad in an angle or position that will not cause injury. Good spotters develop their own technique and skill, something of a art in itself. Spotters give the boulderers a little confidence just knowing he's there, and can help a lot in this respect for the spotter to lightly touch the shoulders or back to reassure the climber. This is not just for reassurance, but adds the sense of touch input to the spotter improving reaction time in the event of a sudden slip off the wall. Also an "assist" can be given to help complete a power move.
Camaraderie. Even though some consider bouldering an individual sport, it is in reality very much a team sport. Spotters are very important and need to work with and know their climber. Many boulderers participate in climbing games together. These games greatly improve overall ability and makes it more fun by adding the social aspect to bouldering. In traditional top rope and lead the climber and belayer are separated by a significant distance. In bouldering they are very close and can interact, talk, give advice, encourage, as well as ask advice, warn before falling, etc. The interaction and beta about how to complete a sequence is what makes bouldering fun.
Benefits. If you get involved with a group of guys/gals doing bouldering you will see a dramatic improvement in your power and strength. You will also see your route problem solving skills improve. Almost all climbing gyms have a bouldering area and have training routines or sequences designed specifically for improving bouldering ability and enhancing your climbing training time at the gym. Bouldering is fun and improves your overall strength, route reading ability, and you will meet some great people. Highly recommend you get into it.