Christmas, Chris tkind or Grandfather Frost. The sending and exchange of Christmas card greetings, observance offasting and special religious observances such as a midnight Mass or Vespers onChristmas Eve, the burning of a Yule log, and the giving and receiving of presents. Along with Easter, Christmas is one of the most important periods on the Christian calendar, and is often closely connected to other holidays at this time of year, such as Advent, the Feast of the Immaculate Conception, St Nicholas Day, St. Stephen's Day, New Year's, and the Feast of the Epiphany