Boxing Day is the 26th of December, a full public holiday, and one of the more genuinely puzzling British exports to countries that took the holiday without ever learning what the name meant.
Where the name comes from
Not from the sport. The most widely accepted explanation is the Christmas box: a gift of money, food or leftovers given by employers to servants and by households to tradesmen — the postman, the milkman, the dustmen. Servants worked on Christmas Day itself serving their employers, and the 26th was the day they were released to visit their own families, taking their box with them.
A related theory points to church alms boxes, opened and distributed to the poor on the feast of St Stephen, which is what the day is still called in Ireland and much of Europe.
What actually happens now
Leftovers
The correct Boxing Day meal is cold turkey, cold ham, pickles, bubble and squeak made from yesterday’s vegetables, and a great deal of cheese. Nobody cooks anything new if it can possibly be avoided. This is arguably the best meal of the entire Christmas period and many British people will say so.
Football
A full programme of football fixtures on Boxing Day is one of the sturdiest traditions in British sport. Clubs are deliberately paired with local rivals to cut travel, so the day produces a run of derby matches. Horse racing — the King George VI Chase at Kempton — is the other fixture of the day.
The sales
Boxing Day was traditionally the start of the winter sales, with queues forming outside department stores before dawn. Online shopping and pre-Christmas discounting have taken most of the drama out of it, but the day is still one of the biggest retail days of the year.
A walk
Somewhere in the afternoon, someone will insist that everyone goes for a walk. It will be cold, it will possibly be raining, and roughly half the party will not want to go. They will go anyway, and afterwards everyone will agree it was a good idea.
The hunt
Boxing Day was historically the day of the hunt. Fox hunting with dogs was banned in England and Wales in 2004, but hunts still gather in town squares on Boxing Day morning in ceremonial dress to follow artificial trails, watched by supporters and protesters in roughly equal measure. It remains one of the more contested British traditions.