What is the religious reason for gift giving on xmas?

What religious tradition does it follow? What does it mean to give a gift on xmas? Is it a more holy gift, have a larger significance?

And what role does Santa play in this? I know Santa is not religious but your granddaughter is so young. Will you take her to have her picture with the red suit guy?

Earl, how do you feel? Have you ever given a xmas gift because it is the "season of giving?"