Santa Claus can actually be traced back to St. Nicholas, a bishop of the early Christian church who was known for his generosity and his love for the children and poor.
One of the stories that made St. Nicholas popular says that St. Nicholas threw his bag of gold through an open window in the house of a poor man who planned to sell off his daughters’ to slavery. The gold served as dowry for his daughters who would have been sold. It is said that the gold landed in the family shoes drying near the fire.
That's why children leave their shoes by the door or hang their socks near the fire place with the hope of receiving gifts.
Santa Claus is important on Christmas because of the custom of giving gifts to children. Santa Claus who is known to appear with huge belly and gigantic heart, wearing red robes and have a long white long beard.