One of your cat's unique characteristics is purring.  At one time, it was believed that the purring sound came from the throat.  It is now believed that purring results from a vibration in the wall of one of the major blood vessels in the chest.  These vibrations, transmitted to your cat's upper air passages, result in a purring sound.  Cats start purring when they are kittens and most of them purr when they are secure, content, or sleeping.  However, some cats may purr when they are ill or frightened. 

Kneading

Kneading is the motion a kitten first makes instinctively when he is nursing from his mother.  It consists of pressing first one, then the other, front paw against the mother's tummy.  Many cats continue to do this as they grow into adulthood.  It is usually a sign of contentment and affection and is often accompanied by purring.  In lieu of the mother cat, your cat will knead anything soft, such as your favorite sweater, comforter, pillow, your lap, or even your hair. 

Claw "Sharpening"

A common misconception is that cats "scratch" to sharpen their claws; however, they are merely satisfying the instinct to stretch and "clean" their claws.  Another reason cats "scratch" is to mark their territory.  They mark their territory in two ways, one by leaving a visible sign of claw marks and two by leaving their scent, which is released from glands between their paw pads.  Your cat will try to satisfy this biological urge regularly and if his scratching post is convenient, he'll leave your furniture alone.  If you're having trouble getting your cat to use the post, try rubbing catnip on it to make it more appealing. 

Curiosity

The house cat, whether purebred or mixed breed, has many characteristics common with his wilder cousins such as the lynx or leopard.  You have only to watch a cat pouncing on a moving leaf to recognize the similarity between him and a tiger pouncing on his prey in the wild.  Keeping this similarity in mind, you can see why your cat does certain things, because they are instinctive. 

Cats are extremely curious.  They will climb into almost anything to explore, which can pose certain dangers, especially if the something is an open trash can full of rain water, a toilet with the lid up, or an empty paper bag which might be stepped on by mistake.  Make sure you check to see that your cat is not accidentally locked in a closet or empty room before you leave your house.  Also, make sure that if your cat goes outdoors to blow your horn and bang on the hood of your car before starting it.  Cats have been known to crawl up under the hood to keep warm. 

Body Language

Your cat uses body language almost exclusively to communicate. Watching how your cat carries herself will help you understand how she's feeling. As you learn, you'll be able to predict her behavior as well. A cat's eyes, ears, and tail all give you clues to what your cat is feeling and thinking. 

Unlike humans, a cat's ears are very mobile.  This allows a cat to communicate with their ears quite easily.  Basic ear positions can alert you to whether your cat is relaxed, alert, defensive, agitated or aggressive. The pupils of the eyes also convey part of a cat's message.  They contract or dilate to indicate mood.   Below are descriptions and illustrations of the different ear poses and eye positions:

When a cat's ears are up (pricked), forward and slightly outward this means the cat is content, relaxed and carefully listening to what is going on around them.  Here the slanted eyes and regularly sized pupils also indicate contentment. 

When something catches a cat's attention the ears become more erect and the cat is alert and ready to investigate the source of the noise.  The eyes become slightly wider indicating alertness.

If a cat becomes anxious or fearful, the ears will point to the sides and flatten.  The more anxious the cat is the flatter her ears will become.  The pupils are now dilated indicating fear.

When a cat becomes annoyed and feels defensive he will turn his ears back.  This should be a warning to you to get back. The eyes confirm this warning with the dilation of the pupils.

When a cat becomes both fearful and aggressive and is ready to fight he will flatten his ears straight back.  It is believed cats pin their ears back in order to protect them during a fight.  The eyes are now greatly dilated since the more fearful the cat the greater the pupils dilate. 

A cat's tail acts as an extension of its thoughts, an indicator of its mood and a warning of intention. . The tail is an important tool for communicating with other cats and with humans. Listed below are various tail positions and their meanings:

When a cat carries his tail high and straight up in the air it means he is proud and content.  A mother cat's upright tail is a signal for her kittens to follow her.

When a cat is relaxed, confident and alert, it walks with its tail horizontally behind it or even slightly drooping. You may also see this tail position when your cat is on the prowl or stalking.

When a cat is very excited and happy to greet its owner he will hold his tail straight in the air and it will quiver or twitch. This is the cat's way of saying he is so pleased to see you that he is overcome with emotion. 

If a cat is friendly but cautious of the other cat or person, the upright tail is hooked over at the tip indicating a degree of uncertainty.

When a cat is fearful and feels seriously threatened he will exhibit what looks like an upright bottle brush (or puffy) tail.  This indicates that the cat has become defensively aggressive; meaning it would rather get away, but if provoked it will defend itself

When a cat swishes its tail from side to side this may indicate real or mock annoyance. It may also be a playful warning saying "I'm going to get you, so look out!" The more emotionally charged the cat is the faster the tail will swish.

Vocalizations

Cats also communicate with humans and each other through vocalization.  Not all meows mean the same thing.  There are subtle and not so subtle differences in a cat's cry that help clue you in on what your cat needs or feels.  The basic meow must be interpreted in the content of the situation.  It could mean, "I want out," Where's my dinner?", or "Will you please get up now, I'm bored." 

A call is when a female chirps or howls mournfully when she is in heat and is seeking a male companion.  There is no mistaking this sound once you have heard it.  A chirr is a "rolled" variation of meow that would be similar to a human rolling their R's.  Mother cats use this to call to their kittens.  It is also a sign of affection and may be used by a cat to call its owner when it is lonely.  Growling, a quiet, low pitched, tone deep in the throat, or hissing indicate that the cat wants you to leave him alone.   Hissing is one of the first warning calls of a cat to tell their opponent to back off. When a cat hisses at you, slowly move away from the cat and do not turn your back to it.