Halloween Traditions & Customs
Bonfires

The word "bonfire" is said to be derived from such "bone fires." Bonfires and sacrifices guaranteed that the sun would burn brightly after a long, dreary winter. It's common to witness hundreds of traditional bonfires in Ireland every year on Halloween Night.
Costumes
Halloween costumes originated from the Celts when they lit huge bonfires and celebrated Samhain by dressing up in elaborate animal skins and heads to disguise themselves as spirits and demons so that the real ones couldn't distinguish them as being human. Their ceremonies consisted of dancing, telling stories, and reading fortunes.
Jack 'O Lanterns

The custom of trick or treating evolved in Ireland, centuries ago. In preparation for All Hollow's Eve, the poor would call upon the rich folks and request money, gifts and food. The food was gathered for a huge feast and celebration.