I’m going to talk about the history of Halloween . There are two stories about Halloween history.

One story is Celtic people’s custom in Ireland is beginning of Halloween. Celtic people live in Ireland. October 31 is the end of a year for Celtic people. People believed the ghost will visit their house, and a witch appears on this night. Then people wore masks, and made a fire to defend themselves.

Other story is the word “Halloween” comes from “All Hallows Eve”. “All Hollows Day” or “All Saints Day” is Celtic festival on November 1. The festival originated from ancient England and Ireland to mark the beginning of the Celtic New Year.

In America, immigrants from Europe spread Halloween to America, but some immigrants brought in a variety of Halloween. So some cultures are integrated into now American Halloween style.
http://ja.wikipedia.org/wiki/%E3%83%8F%E3%83%AD%E3%82%A6%E3%82%A3%E3%83%B3