Vaulting is how survivors cross windows and pallets during a chase. The speed of the vault depends on the angle and distance of approach: a straight fast run-up gives the quickest vault, a slower approach gives a slower one.
Windows are a renewable version of a pallet - they can be used repeatedly, though the game blocks a window that is vaulted too many times in a single chase to prevent genuinely infinite loops.
Vault timing is one of the clearest technical skill gaps between players. Getting the fast version consistently, at the right moment, is worth real seconds in a timed chase.