Halloween is an annual holiday observed on October 31. It has roots in the Celtic festival of Samhain and the Christian holiday All Saints' Day, but is today largely a secular celebration.
Common Halloween activities include trick-or-treating, wearing costumes and attending costume parties, carving jack-o'-lanterns, ghost tours, bonfires, apple bobbing, visiting haunted attractions,
committing pranks, telling ghost stories or other frightening tales, and watching horror films.
(Source: wikipedia.org)