Christmas or Christmas Day is a holiday observed generally on December 25 to commemorate the birth of Jesus, the central figure of Christianity. The date is not known to be the actual birthday 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, 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.

Although nominally a Christian holiday, Christmas is also widely celebrated by many non-Christians, and many of its popular celebratory customs have pre-Christian or secular themes and origins. Popular modern customs of the holiday include gift-giving, music, an exchange of greeting cards, church celebrations, a special meal, and the display of various decorations; including Christmas trees, lights, garlands, mistletoe, nativity scenes, and holly. In addition, several similar mythological figures, known as Saint Nicholas, Father Christmas and Santa Claus among other names, are associated with bringing gifts to children during the Christmas season.

Because gift-giving 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.

The Nativity of Jesus, or simply The Nativity, refers to the accounts of the birth of Jesus in the Canonical gospels and in various apocryphal texts. It is the basis of Christmas, which is an important Holy day celebrated by Christians worldwide.

The accounts of the Nativity of Jesus in the New Testament appear in only two of the four Canonical Gospels, namely the Gospel of Luke and the Gospel of Matthew. Events preceding the birth of Jesus, e.g. The Annunciation to Mary and the Visitation of Mary to Elizabeth appear almost entirely in the Gospel of Luke. The account of the birth of Jesus in Bethlehem appears in both the Gospels of Matthew and Luke - which also includes the Adoration of the Shepherds by itself. The follow on events such as the Adoration of the Magi and the Flight into Egypt appear mostly in the Gospel of Matthew.