What does it really mean when cats wag their tails?

[TheOriginalFAB]

Mine is wagging hers rather fiercely having just bitten me and is really glaring at me too. I know she is trying to tell me something but what?

She's really pissed off about something basically! Why did she bite you?

I had a little stroke as she came to me and then I was rubbing her leg. She then bit me. She is still banging her tail.

You touched her in an uninvited manner, you have pissed her off and she is letting you know it.

Cats wagging their tails in a strong manner are not happy with you - now she has bitten you you will realise this is future - and a lot of cats don't like being touched on their legs or paws

I love touching my cat's paws and sometimes she will let me do it but sometimes the tail starts wagging and that means 'back off before I am forced to use your hand as a kebab'

My cat wags her tail all the time, a bit like a dog. It doesn't mean she's angry.

The disturbing thing is when she backs up her arse really close to you and shakes it. I presume it's some sort of sexual thing and I want no part of it!