Many believe Halloween originated in Europe and especially Ireland. Not true!
The origins of Halloween can be found in ancient Roman festivals where sacrifices (usually livestock), prayers and food were offered to honor the dead. Religion was important to everyday life in Rome. People had their own shrines within their homes.
Halloween customs have been borrowed from two Roman festivals, Feralia and Pomona. Both were held at the end of October. The apple is a symbol used in Pomona, who is the Goddess of fruit. "Bobbing for Apples" is a Halloween tradition taken from the Roman Pomona. The dead were honored in ancient Rome with the festival of Feralia.
When the Romans invaded and occupied British territories from 43 AD until c. 410, the practices of Feralia and Pomona were combined with the Celtic celebration of Samhain.
Actually the activities became a mix with Celtic celebrations.
What usually happens when ancient customs change to modern ones is that the custom stays the same, but the reasons that people give for doing it change. The Medieval Church knew this and worked to give folk customs Christian meanings rather than trying to eliminate them outright.
The Church gave Halloween its name when it changed me celebration of the Roman Festival of the Dead from February to November 1--a Church holiday known as All Saint's Day. Another way to say All Saint's was All Hallows because the term "hallows" means "holy people." The evening before the holiday, October 31 became known as All Hallows Eve, and the church service performed on that evening was called All Hallow e'en.
THE JACK-O'-LANTERN Any trick or treater knows that there's candy at a house with a glowing Jack-o'-lantern on the porch. The light of the Jack-o'-lantern was originally a lamp lit to guide dead souls to the meal left out for them.
The "Jack" in Jack ("of" or "with a") lantern was originally a name for a night watchman carrying a light. But it also came to mean a spirit who floated through the dark as a mysterious ball of light or ghostly glowing face who tried to trick travelers into following him away from the road and to their doom.