Answer:
Rudolph helps to pull the sleigh and can use his shiney red nose to light the way when Santa needs it.
Rudolph has a bright red nose that glows so bright that it lights the way for Santa's sleigh, pulled by eight reindeer; Dasher and Dancer, Prancer and Vixen, Comet and Cupid, Donder and Blitzen.
Rudolph is the most famous reindeer of all; he saved Christmas one stormy night - after Santa decided he could not safely take the reindeer into the storm, due to darkness. Rudolph led the way.