Christmas, Christian festival celebrated on December 25, commemorating the birth of Jesus. December 25 was identified by Sextus Julius Africanus in 221 ce as the day on which Christmas would be celebrated, and it was celebrated in Rome by 336 ce. During the Middle Ages Christmas became extremely popular, and various liturgical celebrations of the holiday were established. The practice of exchanging gifts began by the 15th century. Traditions featuring the Yule log, cakes, and fir trees derive from German and Celtic customs. In the United States and other countries since the early 20th century, Christmas has also been celebrated as a secular family holiday, observed by Christians and non-Christians alike, devoid of Christian elements and marked by an elaborate exchange of gifts and the legendary figure of Santa Claus (see St. Nicholas).