Boxing Day got its name when Queen Victoria was on the throne in the 1800s and has nothing to do with the sport of boxing.
The name comes from a time when the rich used to box up gifts to give to the poor.
Boxing Day was traditionally a day off for servants, and the day when they received a special Christmas box from their masters.
The servants would also go home on Boxing Day to give Christmas boxes to their families.
The day also has religious connections and is celebrated as Saint Stephen's Day in Ireland and the Catalonia region of Spain.
In some European countries - such as Hungary, Germany, Poland, and the Netherlands - Boxing Day is celebrated as a second Christmas Day.
Churches also played a part in the creation of Boxing Day. Through the year they would take money from churchgoers in the form of a collection and hand it out at Christmas.
Many of them stored the collection money in a box, which they opened on Christmas Day. The money was then handed out to the poor the next day - on Boxing Day.
Today, those boxes aren't as popular. However some people leave out extra money for people like paper boys and girls in the weeks before Christmas, and call it a Christmas box.
Boxing Day is the day after Christmas Day and falls on 26 December.
It's also a public bank holiday in the UK.
When 26 December is a Saturday, the Boxing Day bank holiday is moved to the next Monday.
If 26 December falls on a Sunday, then the holiday is the following Tuesday.
Boxing Day Traditions
Christmas Day is now a football-free zone, but this wasn't always the case.
In the days before TV, there would be a full programme of matches on 25 December with fans popping on hats and gloves to watch football at grounds across the UK after eating.
But throughout the 1950s, attitudes towards playing sport on Christmas Day changed.
The final Christmas Day football match took place in 1957, leaving Boxing Day as the traditional festive fixture.
If families aren't going to the football, many spend Boxing Day getting up early to get a bargain from the shops in the Boxing Day sales.
Or maybe they are just taking back unwanted presents...
In the past, Boxing Day sales made it one of the busiest shopping days of the year. And while it is still popular, the growth of big discounts right before Christmas and on special days like Black Friday have stopped December 26th being the mega-spending day it used to be.
For many people Boxing Day actually only means one thing - leftovers!!
Let's face it, many people prepare way too much food for Christmas Day and end up eating it for the next week! Turkey curry, turkey pies and the famous turkey sandwich.
Yum, looking forward to it already - we'll skip the leftover sprouts though...