Boxing Day is another bank holiday that the British have off and it is always the day after Christmas. If that is on the weekend, it will fall on the next weekday.
In Victorian times, tradesmen would come by and collect their boxes or gifts for their good service. It is a day where wealthy landowners gave their servants to have the day off with their families. They were given boxes and leftovers to take home with them. Also churches would collect donations and distribute it to the poor.
Now families often take this as another day to spend together with a quiet meal, which is usually leftovers, and watch sports. Families often head out for a walk as well. While others go fox hunting. Fox hunting has now been banned but hunters will still go out while the dog chase and artificial scent. Also, sales usually begin on Boxing Day, this the UK equivalent to the Black Friday, so shops can clear out their Christmas stock just like in the States so it can be very busy!
All the Best!
American to Britain