When I was growing up, I always looked forward to December 1. Not only did it kick off the month that held both Hanukkah and Christmas (we were a Chrismukkah family) but, more important, it was the day I got to open the first door of my cardboard Advent calendar.

The chocolate behind each panel wasn’t very good (in fact, you might describe it as “meh”), but that wasn’t the point. For me, it was all about the ritual: an annual tradition that not only allowed me to have dessert before breakfast, but also helped build my excitement for the coming holidays.

But as many times as I’d opened those little doors, I’d never once stopped to think about the origins of this tradition. This year, to rectify that, I called Bruce Forbes, a professor emeritus of religious studies at Morningside University and author of “Christmas: A Candid History.”

The word “advent,” he explained, is Latin for “coming.” The Advent period falls in the weeks leading up to Christmas and spans different dates, depending on your denomination. Advent started out as a religious observance that was similar to Lent: a time of somber spiritual preparation and fasting. Over time, Dr. Forbes said, it became “more festive” — perhaps because medieval Europeans needed a reason to celebrate during cold, dark winters.

Counting down the days from Dec. 1 to 25 specifically began in a limited way in 1850s Germany, said Esther Gajek, a lecturer in cultural anthropology at the University of Regensburg. (She personally owns more than 3,000 Advent calendars.)

“Some parents — mostly Protestant ones, mostly in cities, mostly members of the educated classes — made something for their children to visualize the endless time before Christmas,” Dr. Gajek said.

Each day, these children might have hung one picture on the wall, or placed one paper “leaf” on a small wooden Advent tree, or erased one chalk line from a set of 24 on the floor.

In 1902, the tradition went commercial, with a Protestant publishing house releasing a paper “Advent clock.” The following year, a German lithographer named Gerhard Lang printed a sheet of 24 pictures that children could cut out and stick inside an accompanying frame. It was “an enormous success,” Dr. Gajek said.

Following World War I, the popularity of Advent calendars increased, with Mr. Lang exporting them to Britain and introducing a chocolate-filled variety that, many decades later, would become a staple of my own Decembers.

It’s no wonder Advent calendars are so beloved. Even though they have their roots in Christianity, they have since become an all-purpose way to mark the season, featuring everything from Dolly Parton to wine. And a good countdown is culturally agnostic. Just think of the 10-second frenzy before ringing in the New Year.

Now that I’m an adult, the holidays aren’t quite as simple as they once were; feelings of loss and stress come marching hand-in-hand with merriment and cheer. But Advent calendars remind me that the weight of holiday joy need not rest on a single party or gift or day.

Instead, the spirit of the season can be savored slowly: kind of like that mediocre piece of chocolate melting on my tongue.