If you climb a ledge (without jumping) and shield a damage source at the end of the animation (2 frame window) you will activate the Ledge Cancel.
This glitch makes Link ignore the hitbox of many actors and can also make camera the camera zoom out really far. This allows you to walk through boulders and most NPCs. The glitch will be cancelled if you jump normally off a ledge, but you can sidehop or backflip and keep it.
It can also be performed by climbing a ledge out of deep water:
The first known use of ledge cancel was escaping the forest.