Christmas or Christmas Day is an annual festival commemorating the birth of Jesus Christ, observed most commonly on December 25 as a religious and cultural celebration among billions of people around the world. A feast central to the Christian liturgical year, it is prepared for by the season of Advent or Nativity Fast and prolonged by the Octave of Christmas and further by the season of Christmastide. Christmas Day is a public holiday in many of the world's nations is celebrated culturally by a large number of non-Christian people and is an integral part of the Christmas and holiday season. The end of December was a perfect time for celebration in most areas of Europe. At that time of year, most cattle were slaughtered so they would not have to be fed during the winter. For many, it was the only time of year when they had a supply of fresh meat. In addition, most wine and beer made during the year was finally fermented and ready for drinking.