Here is information on Dragon Ball Z
Okay. There is 3 different planets. Earth, Namek, and Friezas home. There is probably more but I dont know them all. Anyhow, there uset to be a planet named Vegeta. No, no, it wasnt named after Prince Vegeta but after his dad King Vegeta. Frieza was the most powerful being in the universe. He held all the sayiens, making them take over other planets and using them for his deeds. Frieza comes in the planet and kills all the sayiens. Atleast he thought he did. He sparred Prince Vegeta, Nappa, and Radditz. All of them are still with Frieza under his power. Before the planets destuction, a baby sayien, was sent to conquer Earth for Frieza. Frieza didnt know this. The baby landed on earth and was about to do what it was told till it bumbed its head and had some amnesia over the whole ordeal. His name is Goku or Kakarot. His sayien name is Kakarot and Earth name is Goku. He grows up to be this very strong warrior. Only fighting on goods side. He is raised by his grandpa Gohan till he dies and Master Roshi takes care of him. He has a best friend named Krillin and a wife named Chi-chi. Later on he has a son named Gohan (after his Grandpa). His son has a tail. All sayiens have tails. Even Goku but he had it permently removed. When a sayien looks at a full moon with there tail. They turn into a very powerful, weremonkey.
Notice his tail. All sayiens are born with a tail.
Also, all sayiens, half and full blooded, can turn into a super sayien. They turn into these by having a extreme emotion. Like when Krillin got killed by Frieza, Goku sort of snapped and just let it all out and turned super sayien. So, when they want to turn super sayien all they have to do is think of something that makes them mad. When they have another extreme emotion while in super sayien form, they will go into stage 2 and 3 and so on. There last form is 4. It is when a sayien sees the light of the sun off the earths surface and turns into a golden weremonkey. It is the most powerfulest form.
This is how most sayiens commonly wear thier tails.