Halloween is based on the old Celtic festival of Samhain which means summer’s end and marks the end of the Celtic year.
It is a time for winter preparation when surplus animals were slaughtered and preparations made for the long winter nights and the dead season when the land sleeps. Because it is a time of transition, going from light to dark, it is also the time when the veil between the living and the dead grows thin and one can communicate with the other.
After the Celtic world became Christianised, all the pagan festivals were replaced with Christian ones so Samhain became All Hallows, (1st November) and All Hallows Eve (Halloween), 31st October.
When I was growing up in the fifties and sixties, Halloween was rarely celebrated in the UK but has grown very popular during the last twenty or thirty years. Few really understand its origins and any mischief afoot usually originates from the consumerism that surrounds it rather than anything of a supernatural nature which is true of most of the ills in the world. Man having the happy ability to shift the blame for his actions onto the devils and demons of the underworld!