Halloween is celebrated on October 31.
It is a very big holiday.
In Halloween we usually use costumes,we use costumes because of a belief that in Halloween the dead people come alive to take reveange to the ones who killed them so we disguise like whitches and like dead persons so when the dead people come alive they don't kill us because they think we are dead too.

The word Halloween is first attested in the 16th century and represents a Scottish variant of the fuller All-Hallows-Even, that is, the night before All Hallows day.

Trick-or-treating is a customary celebration for children on Halloween. Children go in costume from house to house, asking for treats such as candy or sometimes money, with the question, "Trick or treat?"

Finally this holiday is celebrated all around the world.