A Christmas calendar can be in the shape of a gift calendar – or as a calendar with doors. The traditional Christmas calendar consists of two pieces of cardboard on top of each other. 24 doors are cut in the top layer, which means that you can open a new door each day and find a hidden picture. Calendars with "count-down" to Christmas are a relatively new idea. The first "cardboard calendars" in Denmark were available in the 1920s and 1930s, and they were printed in imitation of German/British examples.
A variation of the Christmas calendar is the Christmas calendar with candy, where there is a piece of chocolate or the like behind each of the 24 doors.
The gift calendar is a calendar where there is a small gift for each of the 24 days until Christmas. Often, it is a partially homemade calendar, where the gifts have been purchased separately. A variation of this calendar is the advent calendar with a gift for each Sunday of Advent.
The scratch calendar is a combination of scratch cards and a Christmas calendar. There are also electronic Christmas calendars on the internet. Thus, the Christmas calendar has kept up with technological development, but has still remained a primitive time measurer.
The Christmas calendar concept also exists on TV. Here, the Christmas calendar is usually a TV series - consisting of 24 episodes - where Christmas is a central theme. Each day of December until Christmas Eve, one episode is aired. DR started what quickly became a tradition in 1962 with the Christmas calendar Historier fra hele verden (stories from all over the world).
Right from the beginning, this tradition was aimed at children, and the TV series was supported by an ordinary Christmas calendar, which from 1977 was called Børnenes U-landskalender (the children's Third World calendar), and can be purchased everywhere. The reason for the name is that the proceeds from the sale of the calendar go to a charity, often in the shape of a project in a Third World country.
From 1990, the channel TV 2 also started offering Christmas calendars. Furthermore, this channel expanded the concept, as the launched the first real Christmas calendar for adults the same year, Jul i den gamle trædemølle (Christmas in the old treadmill). That also became Også det blev en succes, which was repeated the following years, even though it took ten years before DR launched its first Christmas calendar for adults.