Climbing ascent styles
Trad is short for 'traditional', in climbing terms.
This is quite a British way of climbing, unlike sport climbing it does not have any pre-placed protection (gear), all is inserted by the leader. The second then removes the gear so the route is 'cleaned' so it is in the same way as prior to the ascent. A nut key may be required if cleaning as protection may get almost welded in place! Many people think that bolting a route makes the rock look ugly and less natural, and so disagree with it. Trad is rarely recommended in chossy areas like quarries as the protection might come out along with the holds and end up with you decking.
The full set of gear used for climbing a particular style is known as a rack, for traditional climbing this includes a full sport rack and the parts known as protection. Protection can be broken down in to passive and active, one is a bit more reactive. A typical trad rack includes
Extenders (Quickdraws) - including extendables 1/2 Sets Nuts Set of Hex's Many slings 60/120/240 (possibly a cordlette) Lots of screwgates Some Friends