Where Did Halloween Come From?
Halloween actually started as two separate religious holidays from the Romans and the Celts. October 31st was a day to honor the goddess of the fruit trees, Pomana. A large feast was held in Roman culture.
Later, the Celtic priests known as Druids celebrated the lord of the dead, Samhain on November 1st. Eventually it was decided to celebrate both deities on October 31st and November 1st.
The Druids thought that on the day before November 1st, Samhain called all the evil spirits to roam the Earth whom had been condemned to the bodies of animals the entire year prior. The people, being afraid of the spirits began to sacrifice for Samhain on October 31st. They would go door to door asking for treats and gifts to their lord. Thus trick or treating came about.
I know what you're thinking. Okay, well, where did the Halloween name come from? November 1st is All Saints Day in the Catholic religion. The day before was known as All Hallows Even and has since been contracted and shortened to Halloween.
As you can see, Halloween did not just come about over night. It was a combination of many different ideas. Some have been added, some have been left out to form what we now celebrate as our modern day Halloween on October 31st. Confusing, yes but somehow we made it all come together.