Though climbing takes many forms-rock and ice, indoors and out, small cliffs and giant mountains-roped climbers almost always follow the same safety procedure for ascending a route. This is the belay system.
Most roped climbs begin at the bottom of a cliff or route, when the leader (the first climber) starts up the rock. As the leader climbs, the rope trails behind. The leader clips the rope into protection (either permanent or removable) as he ascends. The second climber, the belayer, uses a belay device that connects to his harness and the climbing rope. The belayer uses this device to feed out rope or take in slack as needed. If the leader falls, the belayer will catch him using this device.
With modem protection, falls have become an accepted risk on many climbs. Some climbers try a route many times before they can climb it without falling. There is always some danger with falling, but attentive belaying and proper equipment keep the danger to a minimum. Technical climbing and lead belaying require training and should be taught by a qualified instructor.
Once the leader reaches the top of the cliff or the end of the rope, he either is lowered by the belayer or belays the second climber from an anchor. The second climber removes the protection placed by the leader, leaving behind only fixed protection such as pitons or bolts. When the two are reunited, they descend (if they have reached the top) or continue on the next pitch (rope length). By doing this, a two-person team can climb cliffs hundreds or even thousands of feet high.