Cat Tail Signals

I've always been a "dog person," but when little daughter MJ wanted a kitten from her first grade teacher, I relented. That kitty (named "Pumpkin" by MJ but "Psycho" by older sister AE, which is the name that stuck) suddenly died when she was 7. So we got another kitten for MJ, thinking she was heartbroken--that is Gracie. Oddly, Gracie likes me best of all, especially when I'm reading--that's when she wants me to pet her. MJ and Gracie are indifferent to each other.

So I need this info about what signals cat tails give you, as I don't really know!
Your cat's tail is an indicator of its mood and if you observe the tail's movements, you can learn many things from these signals. There are a number of tail signals that the cat can display:

• Tail curves gently down and then up again at the tip:
  This is a peaceful, relaxed cat.
  
  
• Tail raised slightly and softly curved:
  Something has caught your cat's interest.
  
  
• Tail held erect but with the tip tilted over:
  Your cat is in a friendly, greeting mood but may have some reservations.
  
  
• Tail fully erect with the tip stiffly vertical:
  This is a very intense greeting display and has no reservations.
  
  
• Tail lowered fully and possibly even tucked between the hind legs:
  The cat feels defeated or submissive.
  
  
• Tail lowered and fluffed out:
  The cat is showing fear.
  
  
• Tail swished violently from side to side:
  This signal indicates that the cat is very angry.
  
  
• Tail held still, but with tip twitching:
  This signal shows the cat is mildly upset.
  
  
• Tail held erect with its whole length quivered:
  The gesture appears to show happiness or friendliness usually given to its owner as a greeting. It is also the same type of gesture used in territory marking (used by whole males).
  
  
• Tail held to one side:
  This is displayed by a female cat in heat.
  
  
• Tail held straight and fully bristled:
  This signal is one of an aggressive cat.
  
  
• Tail arched and bristled:
  This signal is one of the defensive cat.

Found here.