A nativity scene may be used to describe any depiction of the Nativity of Jesus in art, but in the sense covered here, also called a crib or manger in the UK and creche in France (meaning "crib" or "manger" in French), it means a three-dimensional commercial or folk art depiction of the birth or birthplace of Jesus, either sculpted or using two-dimensional (cut-out) figures arranged in a three-dimensional setting.
Christian nativity scenes, in two dimensions (drawings, paintings, icons, etc.) or three (sculpture or other three-dimensional crafts), usually show Jesus in a manger, Joseph and Mary in a barn, stable or cave intended to accommodate farm animals. A donkey and an ox accompany them; besides the necessity of animals for a manger, this is an allusion to Isaiah: "the ox knoweth his owner, and the ass his master's crib; but Israel doth not know, my people doth not consider" (Is. 1:3). The ox and donkey represent the people of Israel and the Gentiles respectively in such depictions. The scene sometimes includes the Magi or Three Wise Men (with or without a camel), shepherds and sheep, angels, and the Star of Bethlehem. The traditional scenes that show the shepherds and Magi together combine two different events in the Gospels:
(1) The shepherds are informed by angels that "for to you is born this day in the city of David, a Savior who is Christ the Lord" (Matthew 2:10-11).
(2) "When saw the star, they rejoiced exceedingly with great joy; and going into the house they saw the child with Mary his mother, and they fell down and worshiped him" (Luke 2:11)
At Christmas time these arrangements are created and displayed in Catholic and Protestant homes, churches and parks. For the Christmas season, two nativity scenes are put on display at the Vatican. The first is put inside the Vatican Basilica. The second, placed in the Piazza San Pietro before the Christmas Tree, was made by Saint Vincent Pallotti.
Many churches and individuals leave the manger empty (without the baby Jesus) until Christmas Day to reflect that Jesus has not yet been born before then.