Christmas is a holiday that has been celebrated for centuries. The exact origins of the holiday are shrouded in mystery, but it is believed to have originated in ancient pagan traditions. In the 4th century AD, Emperor Constantine officially recognized December 25th as the birth date of Jesus Christ, which is why Christmas is celebrated on that day today. Over time, various customs and traditions were added to the holiday, including gift-giving, decorating trees, and singing carols.