A cat eye blink, often referred to as kitty kiss, is a common cat behavior. The cat's eyes communicate information depending on how open the eyelids are, as well as what the eyes do.
A prolonged, unblinking stare between cats is an intimidating gesture that often will cause a lower-ranking cat to turn tail and leave. Aggressive cats can use a long-distance stare to control access to their owned territory. You might not even notice, but the kitties understand that the top cat is "guarding" the hallway that leads to litter box, for example, and so they won't dare challenge and trespass!
Eye Blink Kitty Kisses
The eye blink, in contrast, is a way that non-aggressive cats signal that their intentions are not hostile. Cats blink at each other, as well as the humans they love, with a slow eye blink "cat kiss." Kitties that use this non-threat signal are able to smooth relationships between other cats, and maintain good social interactions.
Try it yourself. The next time you're sitting quietly and notice the kitty across the room gazing at you, look back-and then with great exaggeration, slowly shut and then open your eyes. Chances are, your cat will return the cat-kiss eye blink.