Christian festival celebrated on December 25, commemorating the birth of Jesus .
December 25 had already been identified by Sextus Julius Africanus in AD 221 as the day on which Christmas would be celebrated, and it was celebrated in Rome by AD 336. During the Middle Ages Christmas became extremely popular, and various liturgical celebrations of the holiday were established. The practice of exchanging gifts had begun by the 15th century. The Yule log, cakes, and fir trees derive from German and Celtic customs. Christmas today is regarded as a family festival with gifts brought by Santa Claus (see St. Nicholas ). As an increasingly secular festival, it has come to be celebrated by many non-Christians.