Every cat owner has experienced it: You're curled up on the couch when your kitty approaches, jump on your lap, walks all over your body in search of a comfortable place to sit, and inevitably stick its butt directly in your face. Why?

Whenever experts try to shed light on the baffling abyss of cat behavior, they start by looking at how cats act around their own kind. To be friendly, cats often rub their heads, bodies, and tails alongside one another. It doesn't just feel good; that behavior also exchanges odors from the many scent glands located on the sides of a cat's head, the corners of its mouth, under its chin, on its ears, and importantly on its tail, including at the base and along the length.

Not only will cats rub their own scent on one another, but they'll also sniff their companions to confirm their identity, to see what they've been up to, and generally just say "hello." That includes their butts, which also contain glands that are rich with scent information. Dr. Debra Primovic notes, "Some believe the 'sniff' can actually relieve tension and stress by helping an individual feel more comfortable about the other cat. Two cats living in the same house may smell each other when one comes in from the outside or comes back from the vet to confirm information about the cat's state, including diet, stress, availability for mating, and mood."

The tail position is also really important when it comes to feline socializing. John Bradshaw, anthrozoologist and author of "Cat Sense: How the New Feline Science Can Make You a Better Friend to Your Pet," has researched how cats react to different tail positions and found that cats are more likely to approach and sniff a cardboard cutout of a cat with a tail pointing straight up in the air than one whose tail was horizontal, which led the cat to back away.