When is advent?
The 24 doors of the advent calendar are labelled from today (December 1) until the day before Christmas.
But the season of advent actually started on Sunday November 27 this year. The last day of advent is always Christmas Eve.
Western churches celebrate advent on the four Sundays in the run up to Christmas.
What is advent?
Advent is a Christian season of anticipation during which candles are lit on Advent wreathes each Sunday.
In the Christian calendar, it is the season of preparation for the celebration of Jesus’s birth at Christmas.
Why do we open advent calendars?
The first advent calendars were created by Lutherans as a way to mark the run up to Christmas in the early 19th century.
The Twelve Blessings of Christmas, by Joy Marie and TJ Mills, says: “Early printed Advent calendars had Bible verses behind little cardboard doors.
By the early 20th century, calendars were being manufactured and published in Germany. The tradition has now spread round the world.
Many advent calendars are no longer religious and have secular pictures of Christmas, for example showing Santa and snowflakes.
Research last year found that only 11 per cent of advent calendars were completely religious-themed, with the rest all linked to High Street brands, pop groups or films.
There is huge range of calendars on the market including chocolate calendars and ones with pictures of Christmassy scenes inside.
In Nordic countries such as Sweden and Denmark there is a tradition of having an advent television or radio shows on each day of December.