Short Answer: Because they can!
Cats make it look so easy: leaping or falling from some high shelf or piece of furniture only to land gracefully on all four feet.
But there’s some complicated feline effort that goes into falling with such style.
Cats have a highly-tuned sense of balance and have very flexible backbones (because they have more vertebrae than humans), which allows them to twist their bodies around to right themselves when they fall — an innate ability known as their “righting reflex.”
When a cat jumps or falls from a high place, it uses either its sight or its vestibular apparatus (a balance system located in the inner ear) to determine up from down, and then rotates its upper body to face downward. Its lower body follows suit.