What actually means "Trick or treat?

And how it relates to Halloween

The origin of "Trick or Treat "The Celts tried to appease the evil spirits: ghosts, goblins and demons." Huge "Samhain" bonfires built to light the way for all the spirits find their way into the world of the living. They left food, hoping it would be if, as the spiritual world. If you have not been any thing, then There are evil spirits "things" about life in this house. Druids needed human sacrifices, which went door to door asking for virgin girls. If this has not been found in the home is chosen, then it was a hexagram painted on the door in the blood to show the appointed evil spirits to cause all manner of evil to fall on the house. In some cases, even death.

Halloween : Trick or Treat : Vox Pops : Taunton