gently twitching the tip of its tail. As it performs these actions, it stares at you, checking your mood. This is a cat's way of offering you a passively friendly reaction and it is something which is only done to close family intimates. Few cats would risk such a greeting if the person entering the room were a stranger, because the belly-up posture makes the animal highly vulnerable.
Indeed, this is the essence of its friendliness. The cat is saying, in effect, 'I roll over to show you my belly to demonstrate that I trust you enough to adopt this highly vulnerable posture in your presence."
A more active cat would rush over to you and start rubbing against you as a form of friendly greeting, but a cat in a lazy, sleepy mood prefers the belly-roll display. The yawning and stretching that accompany it reflect the sleepiness of the animal – a sleepiness which it is prepared to interrupt just so much and no more. The slight twitching of the tail indicates that there is a tiny element of conflict developing – a conflict between remaining stretched out and jumping up to approach the new arrival.
It is not always safe to assume that a cat making this belly-up display is prepared to allow you to stroke its soft underside. It may appear to be offering this option, but frequently an attempt to respond with a friendly hand is met with a swipe from an irritated paw. The belly region is so well protected by the cat that it finds contact there unpleasant, except in relationships where the cat and its human owner have developed a very high degree of social intimacy. Such a cat may trust its human family to do almost anything to it. But the more typical, wary cat draws the line at approaches to its softer parts.
Why does a cat rub up against your leg when it greets you?
Partly to make friendly physical contact with you, but there is more to it than that. The cat usually starts by pressing against you with the top of its head or the side of its face, then rubs all along its flank and finally may slightly twine its tail around you. After this it looks up and then repeats the process, sometimes several times. If you reach down and stroke the animal, it increases its rubbing, often pushing the side of its mouth against your hand, or nudging upwards with the top of its head. Then eventually it wanders off, its greeting ritual complete, sits down and washes its flank fur.
All these elements have special meanings. Essentially what the cat is doing is implementing a scent-exchange between you and it. There are special scent glands on the temples and at the gape of the mouth.
Another is situated at the root of the tail. Without your realizing it, your cat has marked you with its scent from these glands. The feline fragrances are too delicate for our crude noses, but it is important that friendly members of the cat's family should be scent-sharing in this way. This makes the cat feel more at home with its human companions. And it is important, too, for the cat to read our scent signals. This is achieved by the flank-rubbing element of the greeting, followed by the cat sitting down and 'tasting' us with its tongue through the simple process of licking the fur it has just rubbed so carefully against us.
Why do some cats hop up on their hind legs when greeting you?
One of the problems cats have when adjusting to human companions is that we are much too tall for them. They hear our voices coming from what is, to them, a great height and they find it hard to greet such a giant in the usual way. How can they perform the typical cat-to-cat greeting of rubbing faces with one another? The answer is that they cannot. They have to make do with rubbing our legs or a downstretched hand. But it is in their nature to aim their greetings more towards the head region, and so they make a little intention movement of doing this – the stifflegged hop in which the front feet are lifted up off the ground together, raising the body for a brief
Brenna Ehrlich, Andrea Bartz