Also called All Hallows’ Eve, Halloween was a hallowed evening observed on Oct 31st. This was the Eve of All Hallows Day (or All Saints’ Day).
In the ancient Druids, there was a 3 day celebration at the beginning of November. On the eve before, they believed spirits of the dead roamed abroad. The Druids lit bonfires to drive away the sprits. In ancient Rome, the festival of Pomona (goddess of fruits and gardens) occurred at about this time of the year.
In ancient Britain and Ireland, the Celtic festival of Sambain was observed on Oct 31st at the end of the summer. This date was also the eve of the new year in Celtic and Anglo Saxon times and was an occasion for ancient fire festivals where bonfires were set on hilltops to frighten away evil spirits. The soul’s of the dead were supposed to revisit their homes on this day. The festival that later came to be in the autumn acquired ghost, witches, hobgoblins, black bats, and demons that were said to be roaming about.
The pagan observance of Sambain influenced the later Christian festival of All Hallows’ Eve (also called Holy Eve), which was celebrated on the same date. All Hallows’ Day was on Nov 1st and was a time in which the church honored Christian Saints. Nov 2nd was All Souls’ Day when prayers were offered for all the dead. Their souls were said to be in a special waiting place called purgatory.
In medieval times The Pagan Sambain and The Christian Hallows were combined. Children went souling from door to door, singing and begging for soul cakes for the wandering spirits. If no treats were offered, beggars or souls played pranks.
Immigrants to the US, particularly the Irish, introduced secular Halloween customs that became popular in the late 19th century. Mischief making on this occasion by boys and young men included overturning sheds and outhouses and breaking windows. In later years the occasion has come to be observed mainly by small kids who go from house to house in costume saying “trick or treat”.
Halloween in the United States is now a commercial holliday. The modern day Church has tried to put a new spin on October 31st, calling this day a harvest festival. This is quite peculiar considering the pagan roots of this holiday were a harvest and new years festival.