That is normaly a big Secret but i think we all know that they Fly with the Magic Dust
Long ago, Santa Claus and the elves discovered the special formula of Magical Reindeer Dust which make them fly. This dust is sprinkled on each of the reindeer shortly before they leave on Christmas eve. It gives them enough magic to fly right around the world. They can fly very fast: at about the speed of a Christmas light.And every time if they come to a House full of Christmas Joy and there are happy childs open her Gifts they are even able to fly faster .
The Reindeer driven by Santa Claus are the only known flying Reindeer in existence. Besides the Magic Dust, Santa's reindeer are fed a "special" diet throughout the year which helps give them the power of flight.
And one thing to know is also only male Reindeers can Fly thats why the ones with the most Talent are Dasher, Dancer, Prancer, Vixen, Comet, Cupid, Thunder ,Blixem and of course Rudolph
This magic corn is given to Santa Claus by a great and wonderful unknown wizard. Through this magic corn, the strength of the
Reindeer is increased threefold, their stamina increased to infinity and their hooves can manipulate the air as though it were solid ground.
All i know is that the most and best used magic in the Dust is ....The Christmas Spirit what grows in every Heart all Year at the Christmas Time and every Dream and wish
When what to my wondering eyes should appear,But a miniature sleigh and eight tiny reindeer,
With a little old driver, so lively and quick,I knew in a moment it must be St. Nick.
More rapid than eagles his coursers they came,And he whistled and shouted and called them by name;
"Now, Dasher! now, Dancer! now, Prancer and Vixen!On, Comet! on, Cupid! on, Thunder and Blixem!
To the top of the porch, to the top of the wall!
Now, dash away, dash away, dash away all!"