Origins
Halloween — it’s a strange name for an even stranger holiday but the name itself actually reveals a lot about the holiday’s origins. Halloween’s oldest iteration is found in an ancient Celtic festival called Samhain. The Celts believed on the night of the festival the boundary between the world of the living and the world of the dead was thinned and ghosts roamed the earth. When Christians came and colonized the Celts’ homeland, they feared the festival’s implications. They replaced the pagan Samhain with a Christianized version of the holiday called All Saint’s or All Hallows Day on November 1. The night before this Christian holiday became known as All Hallows Eve and, eventually, Halloween.

Trick-or-Treating
Those cute little costumed ghouls running around the neighborhood on Halloween night have extensive historical origins. The History Channel’s website says the costumes came from the pagan part of the holiday, when people initially dressed up to fool the ghosts they believed were roaming the earth.

The treat part comes from Halloween’s religious aspect. According to Today I Found Out, a website dedicated to interesting facts, in the Middle Ages these costumed children began going around to neighbors, offering prayers in exchange for handouts in a practice called souling. Over time, both sides of Halloween mixed together with trick-or-treating morphing into the night of fun and scares it is today.