As Halloween draws closer, you might be wondering how the year’s most frightful celebration first started.
For example, when did kids begin trick-or-treating and why do we turn pumpkins into jack-o'-lanterns?
Both are great questions — not to mention the kind of Halloween trivia any self-respecting enthusiast should have in their back pocket should you need to break it out at a costume party or spooky soiree.
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But first, we have to go all the way back to the very beginning.
There are actually a couple of competing theories about the history of Halloween. The most popular is that Halloween is the result of a thousands-year-old Celtic tradition called "Samhain," which marks the end of summer and beginning of winter.
However, Henry Ansgar Kelly, a research professor specializing in medieval and renaissance studies at UCLA, told TODAY that attributing Halloween to Samhain is actually a "false trail" and its origins can be traced back to a Christian holiday instead.
To better understand why — and how — we celebrate, we asked Kelly and Halloween expert Lisa Morton to break down Halloween's origins, along with how costumes, candy and carved pumpkins became associated with the holiday.
What is the history of Halloween — and why do we celebrate it?
According to Kelly, Halloween started in the U.S. somewhere around the 19th century when the Irish came to America, bringing their celebrations, including All Saints' Day, with them.
“All Saints' Day was a feast day on the Catholic calendar,” Kelly said. “November 1 was the day on which you celebrate all the people that have gone to heaven.”
The night before All Saints' Day, people would hold vigils for the souls that hadn’t yet gone to heaven and were trapped in purgatory. In essence, it was night to pray for the dead — and thus Halloween was born.
Lisa Morton, author of “Trick or Treat: A History of Halloween," leans more toward the Samhain explanation, especially since "the stories that the Celts told each other at Samhain are really, really creepy."
However, she doesn't totally disagree with Kelly's thinking. In fact, Morton said that the Halloween we celebrate today likely came about sometime between the Celtic Samhain celebration and All Saints Day.
Though Halloween has been celebrated in the U.S. as far back as 1870s, Morton said that it didn't become popular until the early 1900s when retailers began selling decorations, costumes and postcards in bulk.
How did Halloween get its name?
According to The Oxford English Dictionary, Halloween stems from All Hallows' Eve— or at least it was until 1773, when the Scots began calling it "Hallow-e’en."
But Kelly said that Halloween also translates to "saint evening" in Scottish.
The first known person to put the words together was Scottish poet, Robert Burns, who penned the poem “Halloween” in 1786.
Why do we give out candy on Halloween?
Fun costume parties and trick-or-treating have become synonymous with Halloween, but Morton said that it wasn't always that way.
For many years, Halloween was a night where pranksters tricked unsuspecting people. By the 1930s, pranks escalated to the point that they were costing cities millions of dollars.
"They were smashing light fixtures and setting fires and tripping people on sidewalks, and, in 1933, vandals did so much damage it became known as 'Black Halloween,'" Morton said.
Although many cities considered banning Halloween, they decided to adopt a new tradition instead. Kelly said the U.S. followed Canada's lead: "The idea seems to have been that if you offer treats, the kids won't go around and play tricks."
The bottom line? Trick-or-treating began as a bribe. Kelly said that "it picked up speed in the United States in the '30s and '40s" — and the rest is, well, history.
Why do we dress up on Halloween?
Halloween is an open invitation to dress up as someone (or something) else and play pretend. But where did wearing Halloween costumes come from?
While many people think that wearing costumes comes from the Celts, Morton begs to differ. "We have no evidence whatsoever of that. It is very modern."
The reason why we wear them is somewhat of a mystery to both Morton and Kelly.
In the 1920s, magazines featured kids draped in sheets pretending to be ghosts — but Morton said it's possible that costumes were worn well before then. They may even be linked to an old Christmas tradition where costumed children would perform plays for their neighbors in exchange for treats. Sounds just like modern-day Halloween, doesn't it?
Why do we carve pumpkins on Halloween?
Carving jack-o'-lanterns can be traced back to Ireland and is based on the story of "Stingy Jack," as noted by the Library of Congress.
"Jack was a legendary trickster," Morton said. "There are hundreds of variants of the 'Jack' folktales all over the world."
As the folklore states, Jack, a drunk and deplorable person, cheated death three times and, each time, tricked the devil out of taking his soul. When Jack finally died, he wasn't allowed into heaven and the devil refused his entry into hell. To light his way through the worlds of good and bad, Jack carried around a gourd with a glowing ember inside.
There are several different schools of thought regarding how we started carving jack-o'-lanterns, but the tradition is thought to have started when the Irish started carving faces into turnips to ward off evil spirits.
Once the Irish came to America, they found that pumpkins were much easier to carve. Over time, people came up with clever ways to carve pumpkins, all in an effort to continue warding off evil spirits come Halloween.
This story first appeared on TODAY.com. More from TODAY: