Whenever you walk into a room where a cat is lying down asleep on the floor and you greet it with some friendly words, it may react by rolling over on its back, extending its legs as far as they'll go, yawning, exercising its claws and gently flipping the tip of its tail.
As the animal performs these activities, it will stare at you, determining your mood.
This is a cat's method of offering you a passively friendly response and it's something which is only executed to close family members.
Not many cats would take a chance at such a greeting if the person entering the room were a stranger, because the exposing of the belly position makes the animal extremely susceptible.
So, this makes up the core of its friendliness.
The cat is saying, in effect, 'I roll over to show you my belly to prove that I trust you enough to assume this highly defenseless position in your presence.
' A cat that was more active would rush over to you and begin rubbing against you as a type of friendly greeting, but a cat in a lazy, sleepy mood favors the belly roll demonstration.
The yawning and stretching that goes along with it reflects the sleepiness of the cat; a sleepiness which it's prepared to disturb just so much and no more.
The faint flipping of the tail shows that there's a small element of conflict building up; a conflict between staying stretched out and getting up to greet the your arrival.
It's not always safe to presume that a cat giving this belly up display is inclined to permit you to stroke its delicate underside.
It might seem to be volunteering this option, but often an effort to respond with a friendly hand is encountered with a swipe from an annoyed paw.
The belly area is so well protected by the cat that it finds touch there unpleasant, except in situations where the cat and its owner have acquired a very high level of social closeness.
However, most average cats are leery about their more delicate parts and draws the line when they are approached.