This is not just a picture of a cat’s tail, but when I saw the picture I saw the tail first and the cat second. For me this is mainly about the cat’s tail.
This is another great Helmi cat photograph. The tail is very erect and that can be a form of communication to signal a desire for a friendly encounter. In other words if two cats go up to each other with their tails in the air or if one of the cats has his tail in the air it signifies that the cat wishes to have an amicable encounter. It is a sign of friendliness. The reason might be to avoid hostility. A cat with his tail in the air might be lower in the hierarchy to the other cat and wish to signal that he is happy to remain in that position to avoid receiving aggressive approaches from the other cat.
I am sure humans do similar things every day except we do it without the benefit of a tail and we probably don’t even realize it!
Cat tails come in a wide range of lengths and styles. I just had a thought. An American Bobtail or Manx could not use the tail up position – obviously! I wonder what they do to communicate the same information?
The cat’s tail is used for communication and scent exchange. The tail is also used for balance. In the wildcats you will see some very thick and long tails. Two come to mind immediately: the tails of the snow leopard and clouded leopard. They both have 
extraordinary tails. Both need these tails for balance. The snow leopard spends a lot of time on step, dangerous rock faces chasing prey etc. Great balance is important. The tail acts as a counter balance. The clouded leopard is one of the world’s great tree climbers and excellent balance is required.
You will see domestic cats wag their tails when they are going through mental conflict or indecision. This is a modern version of the tail being used for balance. The need for physical balance has been transferred to the need for mental balance.
The cat breeds with the best tails are Maine Coons. They are magnificently plumed. The Balinese is a slender cat with a close lying glossy coat. But the tail of this cat breed is plumed and glamorous. It stands out in stark contrast to the coat.
