Christmas is an annual festival commemorating the birth of Jesus Christ, observed by billions of people around the world. Christmas Day is on 25th December and in the UK is a public holiday observed religiously by a majority of Christians, as well as celebrated culturally by many non-Christians, and forms an integral part of the annual UK holiday calendar.

The traditional Christmas narrative says that Jesus was born in Bethlehem in a stable. When Joseph and Mary arrived in the city, the inn had no room, and so they were offered a stable where the child was born, with angels proclaiming this news to shepherds, who then spread the word.

The date of the birth of Jesus is a topic of some debate. In the early fourth century, the church fixed the date as December 25,the date of the winter solstice in the Roman Empire. It is nine months after Annunciation on 25 March, also the Roman date of the spring equinox. Most Christians celebrate on December 25 in the Gregorian calendar, which has been adopted almost universally in the civil calendars used in countries throughout the world. However, some Eastern Christian Churches celebrate Christmas on December 25 of the older Julian calendar, which currently corresponds to January 7 in the Gregorian calendar. For Christians, celebrating that God came into the world in the form of man to atone for the sins of humanity is more important than knowing Jesus Christ's exact birth date.

The customs associated with Christmas in various countries have a mix of pre-Christian, Christian, and secular themes and origins. Popular holiday traditions include presents, cards, Advent calendars, carolling, Nativity plays, midnight church, a special meal,decorations, Christmas trees, Christmas lights, nativity scenes, poinsettias, garlands, wreaths, mistletoe,and holly.

Additionally, several related and often interchangeable figures, known as Santa Claus, Father Christmas and Saint Nicholas are associated with bringing gifts to children during the Christmas season and have their own body of traditions and lore. Because gift-giving and many other aspects of the Christmas festival involve heightened economic activity, Christmas has become a significant event and a key sales period for retailers and businesses. Over the past few centuries, Christmas has had a steadily growing economic effect in many regions of the world.

Source: Wikipedia