Do cats always land on their feet?
Usually. Cats have an innate ability to orient themselves in mid-air so that they land on their feet. This is called the righting reflex. The longer the fall, the more likely a cat is to land on its feet. If the distance of the fall is too short the cat might not have enough time to rotate into an upright position.
Cats accomplish this feat because they have a very flexible spine and no clavicle (collarbone). They make use of rotational inertia by pulling their legs in or extending them out. As a cat falls it will first turn its upper body so that it can see the ground. In addition to visual cues it uses its inner ears to help determine orientation. It then counter-rotates the lower half of the body into an upright position and extends its legs downward.