There are 9 different reindeer their names are
Dasher,Dancer, Prancer, Vixon, Comet, Cupid, Donner, Blitzon and Rudolf.
The reason you put out cookies, milk and carrots is because rudolf likes carrots and santa likes cookies and milk.
It is not just milk and cookies you have to put out. You also have to put out reindeer dust so that rudolf can see your garden at night.
Santa will always know when you are awake or asleep so go to sleep fast.