Halloween has its roots in the Celtic people and their festival of Samhain (which is pronounced SAU-an). It was a magical time, according to the author David Skal.
Gathering around a huge bonfire, on Samhain, Celtic villagers would send the spirits of the dead back to the "spirit world" - an effort to keep them away from living people.
Then ... in the 7th century - as the influence of the Catholic Church grew - the Celtic holiday of Samhain was merged with a religious holiday known as "All Saint's Day" (during which people honored the memory of dead saints and martyrs). "All Saints Day" was celebrated on November 1st.
The original name for "All Saints Day" was Hallowmas - meaning "holy" or "saintly" (for "Hallow") and "mass" (for "mas"). Hallowmas, roughly translated, therefore means "Mass of the Saints." The night before Hallowmas - October 31st - was known as "All Hallows' Eve" (which gradually became "Halloween").
In the mid-nineteenth century, when the Irish Potato Famine devastated Ireland, millions of starving people fled their country. Some of those Irish immigrants - along with their cultural traditions - came to America. One of their traditions included playing pranks on Halloween (with children wearing masks so they would not be recognized).
As the years passed, childish pranks and tricks turned into serious acts of vandalism. By the 1930s, young hooligans were demanding the payment of candy ("treats") in exchange for not damaging people's property ("tricks"). One could say, therefore, that collecting candy on Halloween began as a "form of extortion."
By the late 1930s, as children went door-to-door in their neighborhoods, "trick or treat" became the Halloween greeting. And ... so it remains to this day.
Credits
Clip from "Halloween Unmasked," online courtesy National Geographic.