The worst day of the year is probably the day after Christmas.

You spend the last 48 hours having fun with your family. They wrap and exchange gifts, eat food, watch sports and just have a great time.

Then suddenly the day is over and for many people reality is back. The Christmas music falls silent. The film marathons are suddenly over. You’re kind of back at work.

This is how it normally works in the United States. In many other places, however, the party continues.

It’s Boxing Day, folks.

This is December 26th, which is most commonly celebrated by people in the United Kingdom and Commonwealth countries. Here’s everything you need to know about it.

Wait, what is Boxing Day?

Boxing Day is a public holiday celebrated on December 26th in the United Kingdom and Commonwealth countries.

It is a continuation of the Christmas holidays. It serves as another reason for celebration and gift giving at the end of the year. There are Boxing Day sales and shopping offers to take part in. It’s also a big sports day with football, cricket, rugby, horse racing and more.

Wait, it includes all of these sports but not actual boxing?

NO! Let’s get this out of the way: The holiday has nothing to do with boxing. Nothing at all.

Seems like a pretty big mistake!

Maybe yes! But considering boxing has evolved to include one of the Paul brothers fighting decrepit old guys, I probably wouldn’t complain too much about it.

Good point. Where did Boxing Day begin?

The origins of the holiday are unclear.

We know it started in the UK, but that’s just the location. There are two major theories as to how and why the holiday began.

According to Britannica, Boxing Day is a holiday that began through the church. Churches collected donations from parishioners throughout the year and distributed boxes of these donations to the poor the day after Christmas.

However, there’s another origin story that doesn’t seem quite as sweet. According to History.com, the holiday began as a day off for royal servants and aristocrats in the United Kingdom. Since they had to work for the rich on Christmas Day, they were given a day off the following day, December 26th. Along with this day off came boxes of leftover food and gifts from the previous day to give to their families to celebrate the holiday season.

Regardless of its origin, the holiday stuck. And it is still celebrated in the United Kingdom as well as in countries such as Canada, Australia and other countries.

Why is Boxing Day not celebrated in the USA?

The more interesting explanation is that the holiday was never established and celebrated in the United States. It was not until 1871, more than a century after the United States gained independence from the British, that it became an official holiday.

The simple thing is that your boss is currently waiting for you to come back to work.

Be that as it may, Boxing Day is not an official holiday in the United States. Some people celebrate it in their free time and there are certainly some post-Christmas sales to take advantage of. But you probably won’t find any overwhelming Boxing Day events or traditions here.

This article originally appeared on For The Win: What is Boxing Day and why don’t most Americans celebrate it? Everything you need to know