Nuts and cams are placed into cracks in the rock to provide protection whilst trad or alpine climbing. Ice screws provide some kind of protection for winter climbers. And aid climbers will use a variety of thin pitons, malleable copperheads and skyhooks (yes they are actually a thing) alongside the standard nuts and cams. Hexes are primarily used for warding off angry seagulls or annoying everyone else at the crag with the cowbell sound they make, but they do have some uses (particularly for winter climbers) as large lightweight camming nuts that bite in icy cracks.