Christmas or Christmas Day is a holiday (holiday (calendar)) held on December 25 to commemorate the birth (Nativity of Jesus) of Jesus, the central figure of Christianity. The date is not known to be the actual birth date of Jesus, and may have initially been chosen to correspond with either the day exactly nine months after some early Christians believed Jesus had been conceived (Annunciation), the date of the winter solstice on the ancient Roman calendar, or one of various ancient winter festivals. Christmas is central to the Christmas and holiday season, and in Christianity marks the beginning of the larger season of Christmastide, which lasts twelve days (Twelve Days of Christmas).

Although nominally a Christian (Christianity) holiday, Christmas is also widely celebrated by many non-Christians, and many of its popular celebratory customs have pre-Christian or secular (secularity) themes and origins. Popular modern customs of the holiday include gift-giving, music (Christmas music), an exchange of greeting cards (Christmas card), church (Christian Church) celebrations, a special meal, and the display of various decorations; including Christmas trees, lights (Christmas lights), garlands, mistletoe, nativity scenes, and holly. In addition, Father Christmas, so named in parts of England and in France (Pere Noel), known as Santa Claus in many other areas, including Scotland, North America, Australia and Ireland), is a popular folklore figure in many countries, associated with the bringing of gifts for children.

Because gift-giving (Gift economy) and many other aspects of the Christmas festival involve heightened economic activity among both Christians and non-Christians, the holiday has become a significant event and a key sales period for retailers and businesses. The economic impact of Christmas is a factor that has grown steadily over the past few centuries in many regions of the world.