What does my cat's behavior mean?

Question

My young cat has always exhibited some odd movements in her tail.

While it is straight up, she'll quiver or shake it. She could be leaving her scent but I don't know if she has any scent glands in that area.

It also kind of seems like she does it when she is wanting something, such as food or attention.

Answer 1

My cat does this when he is agitated about something or if he is nervous.

Answer 2

Maybe it's time to clean the cat box.

Answer 3

IT COULD MEAN MANY THINGS DEPENDING ON OTHER SYMPTOMS YOU SHOULD GOOGLE IT  

Answer 4

She's sending out signals to the mothership!

Ahem.

Not all behavior serves a specific evolutionary purpose. Think about dogs wagging their tails, or all the myriad "useless" behaviors humans have. Chances are that's just how she expresses excitement.