In the fast-paced modern world, it is often easy to forget the importance of bells in the not-so-ancient past. We have clocks to tell us the time. We have telephones to communicate with each other instantly (maybe telephones are too ancient now too. Cell phones it is.) We have roads we stick to, with cars for our main transportation. We announce our happy occasions on social media.
It wasn't always like that. In small towns and large cities, it was the job a worker in the belfry towers of churches to keep track of the time and ring the bell every quarter of the hour. This told everyone within earshot what time it was. The belfry tower's use extended beyond the mundane though. There were special melodies for funerals. For weddings. For festivals. And perhaps one of the favorite announcements was to herald in Christmas day.
There was a popular tradition that Jesus Christ was born at midnight at he very start of December 25th. As such, there were special Christmas worship services held at midnight, and a special song to announce that Christmas had arrived. Even those who did not attend these masses would listen for the bells from their home. (It wasn't required, given that young children and elderly would struggle, but it was a special thing to attend if one could.)
Another popular winter bell is sleigh bells. Horse-drawn carriages would, by and large, stick to established roads, especially since these roads were difficult to make and maintain. As such, for pedestrians it was fairly easy to avoid them. But horse-sleighs were another story. Yes, they still would travel on the main established roads, but new roads to favorite winter destinations were also forged on fresh-fallen snow. As such, there were a more close shaves between pedestrians and sleighs, as well as unfortunate accidents. Sleigh bells were implemented as a safety precaution, which helped tremendously. As a bonus, now children who were excited for family to visit would listen for these sleigh bells to announce their cousins and grandparents arrival. Now youth waiting for their ride to a winter social would thrill with anticipation when they heard the sleigh bells approaching. Sleigh bells were a seasonal thing more than a Christmas thing, but they did play a role in the general holiday cheer. The famous song "Sleigh Ride" and "Jingle Bells" were originally not written for Christmas, but they gravitated to popular Christmas carol repertoire anyway.
The final kind of bells associated with Christmas are hand bells. In ancient times, hand bells were used to scare away dark spirits, and this played a part in mumming and the Wild Hunt where these spirits were believed to be more active.
Later, hand bells played a more practical role. Not everyone lived close enough to hear the church bells. When there was important announcements to be made, a town crier would play their bells to bring attention to their message. This included suggesting that one might want to get going if they wanted to attend Christmas mass.
Wassailers would also bring hand bells for their Christmas entertainment. May as well let nobleman know you're coming to give them a chance to get to get their treats ready for you. Or, more likely than not, annoy them with your loud sounds until they feed you something tasty! We won't go until we get some, we won't go until we get some! And who wants a large, drunken, rowdy crowd loitering outside one's estate?
(This arrangement Gloucester Wassail the kids stumbled across last night brought back fun memories because I recognized Cory Evan's arrangement when I was in Chamber Singers at Utah State University. And sure enough, he's the conductor of these USU students. I even know the drunkard shown at the end, haha. No bells here, but it does illustrate the spirit of Wassailing very well.)
For more information, here's a nice Christmas bell overview.
And here's more information on Mumming.
Christmas History Advent Calendar
Christmas Bells is day 8.