A toe hook is a technique where you pull with the top of your toes and foot against a hold or feature, using the foot like a hand to maintain tension on steep and overhanging climbing. It's often paired with a heel hook on the other foot to stop the body swinging out on roofs.
A project is a route or boulder at the edge of your ability that you work on over many attempts or sessions — rehearsing moves, refining beta, and building strength — until you can finally send it cleanly. 'Projecting' is the process of methodically piecing such a climb together.
To send a climb is to complete it cleanly from start to finish without falling or resting on the rope or gear. The word covers any successful clean ascent — an onsight, flash, or redpoint all count as sends. 'Sending' has become general climbing slang for nailing a goal.
The crux is the hardest move or section of a climb — the part most likely to stop you. A route's grade is largely set by its crux, and climbers focus their beta, strength, and mental preparation on getting through it. A climb can have one crux or several.
Beta is any information about how to climb a particular route or boulder problem — which holds to use, the sequence of moves, foot positions, rests, and clever tricks. Climbers share beta in person, in guidebooks, and in videos, and using it changes whether an ascent counts as an onsight, flash, or redpoint.
A flash is climbing a route or boulder problem cleanly on your first attempt, but with the benefit of beta gathered beforehand — watching someone climb it, getting hold descriptions, or studying video. It ranks just below an onsight, which allows no prior information at all.
An onsight is climbing a route cleanly from bottom to top on your very first attempt, with no prior practice, no beta, and no watching others on it. It's considered the purest and most prized ascent style, because you solve every move in real time without any foreknowledge.
Flagging is a balance technique where you extend a free leg to act as a counterweight, keeping your body in balance and stopping it from swinging out (barn-dooring) when holds are off to one side. It lets you reach and stay stable without a foothold for the trailing foot.
Mantling is a technique where you press down on a ledge or large hold with your hands — transitioning from pulling to pushing — to lever your body up and over it, much like climbing out of a swimming pool. It's the standard way to top out boulders and gain ledges.
Jamming is the core crack-climbing technique of wedging part of the body — fingers, hands, fists, or feet — into a crack and subtly expanding or torquing it to create a secure hold. Unlike face climbing, jamming uses the crack itself rather than holds on the rock surface.