Toprope Climbing
When a climber uses the term "toprope," he is referring to a technique wherein an anchor is set at the top of the cliff. A rope runs from a belayer at the base of the cliff, up to the anchor and then back down to the climber. As the climber ascends the wall, the belayer takes in rope through his belay device. If the climber falls, the belayer merely locks off his device, arresting the fall. This system is designed to stop the climber's fall immediately.
Toproped climbing is very safe because no one is required to "lead." In most cases, climbers are simply able walk around to the top of a cliff in order to set-up the system.
Lead Climbing
The leader is the first person to climb a cliff. As the leader ascends the wall he drags a rope up that is tied to his harness. As he works his way up a wall he will put in rock protection. After the "pro" is in place, the leader may clip the rope into the gear while the follower belays from below. Should the leader fall, the follower will "catch" him in midair with the belay device.
Of course, if the leader falls 10 feet above the last piece of protection, he will actually fall 20 feet or more before the follower catches him. That makes the leader's job quite risky. Once the leader is on top, he may build an anchor, clip into it and put his partner on belay, essentially providing the follower a toprope.
Lead climbing may be done on both traditional and sport climbs.
Free Climbing
Free climbing does not mean, "without a rope." Conversely, free climbing absolutely requires a rope. The defining characteristic of free climbing is that it does not require an individual to pull on protection. The protection exists to keep a climber from hitting the ground should he fall, not to aid the climber on his ascent.
Aid Climbing
The polar opposite of free climbing is aid climbing. When an individual aid climbs, he places a piece of protection and then clips a nylon ladder to it. He then climbs up the ladder and places another piece, repeating the process over and over again. The climber is using direct aid to ascend the cliff face. This is often done when it is much too difficult to free climb.
Trad Climbing
Sport Climbing
The polar opposite of free climbing is aid climbing. When an individual aid climbs, he places a piece of protection and then clips a nylon ladder to it. He then climbs up the ladder and places another piece, repeating the process over and over again. The climber is using direct aid to ascend the cliff face. This is often done when it is much too difficult to free climb.
Big routes in Zion National Park and in Yosemite National Park are commonly aided. These are the massive routes that sometimes require portaledges or bivies on the wall. Big wall aid climbing is in many ways analogous to vertical backpacking. And while most big wall climbs require some free climbing, they tend to lean toward direct aid.
Free Soloing
Free Soloing
Free soloing is the art of climbing without any ropes whatsoever. A fall under these circumstances will result in serious injury or death. Free soloing is incredibly dangerous and is only practiced by a small percentage of climbers.
Trad Climbing
Traditional climbing, or "trad" climbing, is a style of climbing that requires the leader to carry all of his protection with him. In other words, the leader carries an array of camming devices, wired nuts and other assorted odds and ends that might be used to protect the route. Traditionalists will not alter to rock in order to create protection for the leader. In other words, a true traditional route does not have any bolts on it.
Sport Climbing
Sport climbing is a style of climbing that requires significantly less equipment than trad climbing. A sport climb is a route manufactured with bolts. A true sport climb does not require any traditional gear at all.
Many consider sport climbing to be much safer than trad climbing because in most cases the routes have been manufactured in such a way that they are safe for a leader. As a result, this is an incredibly popular form of climbing.
Conclusion
Climbing is an incredibly varied sport and the preceding is only the most elemental breakdown of it from a stylistic perspective. That said, an understanding of this beginner level material will help the novice climber to understand the many conversations about style that take place in the climbing world every day.