Halloween's origins lie in the ancient Celtic celebration of Samhain, celebrated in the region that would later become Ireland, the UK and Northern France.
Few records exist of the holiday but it is thought to have been a pagan festival marking the end of harvest, but also a day when spirits could cross into the human world.
Traditionally held on the 1st of November, many people would dress up the night before and light fires to ward away bad spirits, as well as sacrificing animals, and sometimes humans, as offerings.
People sacrificed animals, and sometimes humans as offerings
Often they would be burned alive while the Celts chanted a thank you for the year's harvest. Think The Wicker Man goes Gregorian.
The huge fires, often whole fields of crops, attracted mosquitoes. These attracted bats, which, it could be argued, might have then attracted black cats, like a real life re-enactment of the Old Lady who swallowed a fly. Unfortunately, there is little historical evidence to support this.
Often whole fields of crops were set on fire
In 1000 A.D. when the Christian church arrived on Celtic land it would sanction "All Souls Day" in an attempt to counter paganism. Festivities were similar to Samhain but focused on the celebration of the dead and the spread of Catholicism. To the relief of many, the church largely discouraged sacrifices.
Many modern Halloween traditions can be traced back to these early festivities. People would left outside their doors as offerings to the spirits, and in the years which followed, people dressed as ghouls and go door to door performing songs or poetry in exchange for treats. Tricks came later, when more modern revellers decided cheapskates were getting off too easy.
People would dress as ghouls and go door to door performing songs or poetry in exchange for treats
The act of pumpkin carving harks way back to Samhain when the pagans carved faces into turnips to ward off evil spirits. It was only later, when Irish immigrants escaping the potato famine brought the tradition to America, that the larger, more malleable pumpkin was used.
The name Jack O' Lantern could refer to when people used to carry lanterns when walking at night. With darkness masking their identity, they were literally "Jack" with a lantern. There are also multiple versions of the Irish tale of Stingy Jack, who tricked the devil so many times that the devil gave him a burning coal from hell to warn others of his devious ways.