CHICAGO (NewsNation) — Grab your broomsticks and get ready to fly, Halloween is Tuesday and there’s much to know about the “spooktacular” holiday before hitting the town on All Hallows Eve.

It’s that time of year again when folks across the nation decorate their lawns with pumpkins and skeletons, apples are bobbed and trick-or-treaters beg on doorsteps for a sweet confection. Most Americans have been taught these traditions since they were kids, but why have they come to follow these rituals?

What is Halloween?

Halloween, the scariest holiday of the year, can be traced back over 2,000 years ago to Ancient Celts who lived in the area now known as Ireland, the United Kingdom and northern France, according to History.

The holiday originated as the Celtic festival of Samhain, which was the midpoint between the fall equinox and winter solstice, according to a Library of Congress blog.

It was a pagan religious celebration to welcome the completion of their harvest. In Gaelic, “Samhain” is translated as “summer’s end,” according to Almanac. The Celts celebrated with large bonfires and prayer, believing that at this time of year, the barrier between the spirit world and the physical world was open.

Much like the celebration of Dia de Los Muertos, the Celts believed it was a time in which their ancestors might cross over to the physical world. Those participating in these celebrations would dress as animals and monsters to avoid being kidnapped by ghosts and fairies, History reported.

In the seventh century, Pope Boniface IV established All Saints Day, or All Hallows’ Day, to commemorate and honor Christian martyrs and saints. This holiday Christianized the pagan holiday by celebrating the souls of those who had died.

It wasn’t until the eighth century that Pope Gregory III designated the holiday to be moved to Nov. 1, the day after the pagan holiday, according to History. It was because of this designation that Oct. 31 became known as All Hallows Eve.

Over time, the day became known as Halloween.

How did Halloween start in the U.S.?

While Halloween is a widely celebrated event here in the States, it almost didn’t make it across the Atlantic. Back when the Puritans immigrated to North America, they disapproved of the pagan roots and didn’t take part in any of its spiritual traditions, Country Living reported.

However, small numbers of American colonials still celebrated the festival in many of the southern colonies, History reported.

It wasn’t until the Irish and Scottish migrated to the country in the second half of the 19th century that the holiday became more custom in the U.S.

Why do we trick-or-treat?

There are three theories behind why people trick-or-treat on Halloween.

Theory 1: During Samhain, Celts would leave food out to appease the wandering spirits traveling the Earth at night, Library of Congress reported. People began dressing up as these spirits in exchange for similar offerings, the report said.

Theory 2: Trick-or-treating began from a Scottish practice of guising — a secular version of “souling.” The Library of Congress blog said children and poor adults would attempt to collect food or money from folks in return for prayers on All Saints Day. The tradition later dropped the prayer aspect and added songs, jokes and “tricks” in order to appease non-religious folks. As the tradition progressed, the costumes also evolved into scarier versions, hoping to spook unsuspecting people, Country Living reported.

Theory 3: The last theory originates from the German-American Christmas tradition called “belsnickeling,” where children dressed up in costume and would see if their neighbors could determine who was hiding beneath the disguise, according to the Library of Congress report. In some cases, food or other treats were given to the child if they could not be identified.

While all theories provide colorful potential origins for the practice of begging for candy one night a year, it wasn’t until the 1900s that trick-or-treating became a mainstream tradition, according to the Country Living report. Adults popularized the idea in hopes it would prevent children from pulling any holiday pranks in their neighborhoods.

Playing pranks on Halloween, otherwise known as “Devil’s Night” or “Mischief Night,” became popular in the early 19th century. It had become a night of tricking and illusion, according to the Smithsonian Magazine. The whole tradition of pranking — rooted in Halloween superstitions — was brought over the the States by Irish and Scottish immigrants, according to the report.

Today, children are often heard saying “trick-or-treat” when greeted by someone giving away candy.

Dressing up in Costumes

This custom is rooted in Samhain rituals. Superstitious Celts would dress up as animals and monsters to avoid being kidnapped by any spirits that may have walked the Earth during Samhain. Some would even go outdoors and make loud noises in an effort to scare spirits away, Almanac reported.

Dressing up in costumes during the Scottish practice of guising also became popular. It wasn’t until young Scottish and Irish pranksters got the idea to spook neighbors that these costumes evolved into scary ones, Country Living reported.

Halloween costumes went mainstream in the 1950s, creating the base for the costumes we know today, History reported. Mass-produced costumes became affordable and more kids wanted to dress up as princesses, mummies and clowns.

Witches, Black Cats and Pointy Hats

Black cats are a popular symbol of Halloween, many believing the superstition that black cats are evil or bad luck. The idea of being spooked by a black cat dates back to the Middle Ages, according to the Library of Congress report.

The black feline creatures were considered a symbol of the devil, and centuries later, a sign that a witch was near, the report said. This idea evolved, and it was believed that cats were witches’ “familiars,” supernatural beings that assisted in their practice of magic.

The fascination and fear of witches have been around longer than the U.S. itself. The fear of witchcraft led to many false accusations and the deaths of dozens of women, especially in the Salem witch trials, History reported.

Over time, witches and their craft began to popularize in American culture, the report said. People began to dress up like the magical creatures, dressed in the classic black, pointy hat and cloak with a broomstick and black cat.

But where did the black, point hat originate, and what does it mean?

The most common root of the hat is associated with Quaker women, where in the 17th century, women wore tall, black, wool felt hats, History reported. However, the Quakers’ beliefs were not popular among the British monarchy or Church. In fact, their beliefs led to mass persecution and imprisonment, History reported.

From this, many Quaker women rarely went out in public and have been represented as isolated women in illustrations.

Jack-O’-Lanterns

One might be surprised to learn that the Halloween tradition of carving pumpkins didn’t actually have anything to do with the gourd itself. Instead, the tradition originated in Ireland with the carving of turnips or radishes instead, Mental Floss reported.

The tradition originated from the legend of Stingy Jack, a man who repeatedly trapped the devil and would only let him go under the condition that when he died, his soul would never go to Hell. Turns out, when he did die, Heaven didn’t want his soul either, Mental Floss reported.

Jack’s soul was then forced to walk the Earth for all eternity, and was given a lump of burning coal in a carved-out turnip to help light his way, the report said.

Over time, people began mimicking this tradition, carving scary faces in gourds to scare off spirits. Many people resulted in putting their Jack-O’-Lanterns on their front porch to keep spirits away from their homes.