Christmas, also referred to as Christmas Day or Christmastide, is an annual holiday celebrated on December 25 that marks and honors the birth of Jesus of Nazareth.  His birth, which is the basis for the Anno Domini system of dating, has been determined by modern historians as having occurred between 7 and 2 BC. The date of celebration is not thought to be Jesus' actual date of birth, and may have been chosen to coincide with ancient Roman solar festivals that were held on December 25.

Modern customs of the holiday include gift-giving, church celebrations, and the display of various decorations—including the Christmas tree, lights, mistletoe, nativity scenes and holly. Santa Claus, also referred to as Father Christmas, is a popular mythological figure often associated with bringing gifts at Christmas. Santa is generally believed to be the result of a synchronization between St. Nicholas of Myra and elements from pagan Nordic and Christian mythology, and his modern appearance is believed to have originated in 19th century media.

Christmas is celebrated throughout the Christian population, but is also celebrated by many non-Christians as a secular, cultural festival. The holiday is widely celebrated around the world, including in the United States, where it is celebrated by 96% of the population.