Just to clarify for those unfamiliar with rock climbing as a sport, when climbing outdoors on real rocks there are a bunch of different types/styles.
The two I would like to differentiate are trad (short for 'traditional') climbing in which a climber has to place pro (short for 'protection') and sport climbing where protection has already been placed. Sport climbing differs from trad climbing in one very important instance; trad climbers have to place their own pro as they go ('pro' is small pieces of metal of varying complexity -- chocks/nuts, cams/friends, pitons/pins -- that are placed into flaws in the rock and to which the rope is loosely attached by a quickdraw -- a strap with a carabiner on each end.
In sport climbing the 'pro' consists of bolts that have been driven into the rock -- usually by volunteers -- to which the climber can clip her/his quickdraw. This allows a climber to extend her/himself further than they could on a trad route because they don't need to conserve enough energy to place their pro -- often a finicky and delicate process -- they simply -- hah! -- need to have enough strength to clip the next bolt to prevent themselves from taking a whipper (a big fall).
There is some debate as to which style of climbing is 'purer', but that's an argument for another node.