The Very Basics
The standard disclaimers about how dangerous climbing is and how unreliable anything is you read anywhere apply here as well. This site is far from definitive (and probably far from accurate). It is here for the amusement of myself and friends and possibly to shed some light, though I don't mind a little obfuscation now and again either. Various parts have been adapted and pilfered from sources found hither and yon, though I have tried to make all entries mostly original. So please read, but remember that responsibility for safe climbing is your own.
The below is a list of terms which are necessary to start to explain what I am on about. Talking about one tends to require knowledge of the others, so, if you are interested, read it through a couple of times.
1. A route
A specific route up a rockface. These are often VERY specific. i.e. "Start at the crack 2m right of the holly bush. Ascend the crack for 10m, then step left onto a ledge. Traverse the ledge for 5m, and then climb the centre of the orange coloured wall for the remaining 5m, using the crack system to gain the top to the right of the ash tree".
Some "lines" (lines=routes) are natural and clear (e.g. "ascend the parallel cracks"), some, like the example above, are contrived.
Routes are given grades, according to their difficulty. Grading is a vast subject/argument in itself, so I'll leave it at that here.
Routes are also given names, generally by the first person to get up them. Hence a route which looks really hard might be tried by various people, but the name and grade are given by the first person to get up it. Grades are sometimes revised. Names, once they have stuck, are not.
2. The leader
Is the person who takes the rope up with them, and belays the second. Leading is often referred to as being on the "sharp end of the rope", as the Leader is essentially taking all the risks. With the rope below them, they have the potential to fall a long way, the are reliant on their protection, which may have been placed when in extremis and may pull out if a fall is taken. The leader has to work out the route, protection and ropework on the move mentally, whilst physically getting up the route, and with the knowledge that getting it wrong may be fatal.
3. The second
The person who follows the leader up, and initially belays him. Much safer than leading in 99.99% of situations.
4. The belay.
The safely system. In (very) short, the rope passes from the climber's harness to their climbing partner, who pays the rope out (if the partner is below the climber) or takes it in (if they are above the climber) as the climber ascends.
The way this is done is the rope passes through a belay device (of which there are numerous) which basically passes the rope through a series of tight bends. The belay device is clipped to the partner's harness. If the climber is climbing normally, the rope runs freely through the belay device, but if the climber falls the additional friction causes the belay device to "lock up" - i.e. not let any rope through.
This means that the load of the falling climber (less any force absorbed by the stretch on the rope (which is lots), and force absorbed by the belay device (which can be lots)) is transferred to the partner (belayer).
The belayer is therefore ideally anchored securely. If they are at the bottom, then their body weight acts against the fall, and although they may be pulled into the air, unless there is a HUGE weight difference it will not be by much. I have been belayed by people half my body weight safely. A few stones difference will not be felt as the rope and belay deice will absorb so much of the force. If the belayer is at the top of the route then unless they are securely anchored they may be pulled over the top, hence multiple secure anchors into the rock are necessary.
5. A belay device.
Partially explained above, they can be fully automatic (a gri-gri). However most belay devices require a degree of competence on the part of the belayer, plus the belayer to be alert and watching (if possible) what the climber is doing. Most belay devices require a manual lock-off by the belayer to stop the rope passing through it in the event of a fall.
That which protects the climber against a fall. Basically, (ideally) secure connections between the rock and the rope.