Cats use many means to communicate. Meowing is the most common form. Cats often meow to assert their presence, which is fine. But it becomes annoying when your cat meows for food or to get into your bedroom at night. Begging for food is a habit that often starts early. What usually happens is that your kitten meows in that adorable kittenish way, you give him food, and he learns there is a cause-and-effect relationship. The habit is formed. The same happens if you let him in as soon as he meows at the bedroom door. The usual advice is to try to avoid giving in.

Sometimes you may notice that your cat seems to be meowing but no sound is emitted. There actually is a sound, but it's too high pitched for humans to pick up. Kittens use this sound to let their mothers know where they are.

Purring is another common form of communication. Cats typically purr to relax. They begin to purr as early as 2 days old. Cats often knead as they purr, a habit formed while nursing. The kneading stimulates the mother's mammary glands to produce milk.

The chirp is a close relative of the purr. You may hear it while your cat is purring and rubbing against your leg. He's telling you that he's very content.

On the other end of the spectrum are the hiss and spit, both warnings for you to stay away. A hissing cat is on the verge of fighting. When a cat spits, he's poised to fight - or run away.

Like humans, cats communicate with us and with each other using body language, especially using their ears, eyes, tails, and fur. The ears of a focused, alert cat are erect. At ease, his ears are relaxed. If he's angry or aggressive, his ears will turn downwards and to the side. Beware! The more frightened he gets, the more his ears will flatten. A fearful or threatened cat will also have dilated pupils. His slit like pupils will become large and round. His tail can give you clues to his mood as well. If his tail is up, you can assume he's comfortable with you. When he wraps his tail around you, he is marking you with scent glands on the upper surface of his tail - a sign of his esteem. A cat with a tail low to the ground is threatened. If he is both frightened and aggressive, his tail will be raised and the hair on the end of his tail will stand up, as well as the hair on his back. He'll fluff up his tail to make it look bushier, to create the illusion of being bigger and "badder" than he really is.

The writers are Dr. Steven B. Holzman, Dr. William R. Haagenson and Dr. Kathleen Tapley. They are associated with the Nassau-Suffolk Veterinary Hospital of Farmingdale.