Tails
Tail held low and tucked between the hind legs	~	The cat is showing defeat or submissiveness ( toward another cat ).
Tail held low and puffed out or bristled	~	The cat is intensely afraid.
Tail still but tip of tail quivering or twitching	~	The cat is mildly irritated or pensive. The cat may attack if the twitching becomes violent enough.
Tail swishing from side to side rapidly or violently	~	The cat is angry and about to attack something, this is seen during fights and play time. This is not the same as tail wagging in dogs.
Tail curved gently downward, then curved up again at the tip	~	The cat is very relaxed , content and comfortable.
Tail straight up or just slightly raised and curved softly like a question mark	~	The cat is very excited and beginning to get interested in something.
Tail straight up and unmoving	~	an unabashed greeting. This is what a mother cat does to her kitten to tell him/her to inspect her rear.
Tail straight up but the tip tilted to one side	~	your cat is very interested and intrigued by something; your cat is happy and friendly.
Tail erect with whole length or tip quivering gently	~	The cat is slightly irritated or pensive.
Tail arched and puffed out or bristled	~	your cat is scared or fearful and is ready to attack or defend itself. The bristling is instinctual as it makes the cat look larger.
Tail straight up in the air and fully puffed out or bristled	~	your cat is angered, aggressive and ready to attack.
Tail straight up in the air and quivering a bit	~	your cat's tail moves this way when spraying urine to mark territory; however, once your cat is spayed or neutered he/she will continue to move his/her tail this way (without any spray or urine being excreted) when you greet him/her. This is your cats way of saying, 'hi, it's your loving cat!'
Tail held to one side	~	your cat is giving a sexual invitation (generally only females in heat do this).