A cat's eyes communicate information depending on how open the eyelids are, as well as what the eyes do. Cats' eyes demonstrate strong emotion, easily recognizable by other cats.

Staring at a cat right in the eyes is aggressive behavior. A prolonged, unblinking stare between cats is an intimidating gesture that will often cause a lower-ranking cat to turn tail and leave, or for a fight to begin.

A slit-eyed look indicates strong emotion - fear or aggression. Squinting also protects eyes from the potential claws of an opponent.

On the other hand, cats with wide open eyes usually indicate friendliness, curiosity, or even playfulness. Their innocence when meeting another is a pleasure to behold.

When your cat does blinks at you very slowly, it is almost like a kitty kiss. It shows affection and devotion. If you blink slowly at a cat, it might return the kiss.