Samhain is an ancient Celtic festival that marks the end of the harvest and winter’s beginning in Ireland, the United Kingdom and northern France. It was also a time when people believed that spirits could cross over into our world easily. They built huge bonfires, wore costumes, and recited verses at their neighbor’s doors to chase away ghosts.

The Samhain festival evolved to include a Roman tradition honoring Pomona, the goddess of fruit and trees. She was represented by an apple, a fruit that still plays a role in modern-day fall and Halloween traditions like bobbing for apples and candied apples.

On the British Isles, Samhain traditions became part of a three-day festival from October 31 to November 2 that included All Hallows’ Eve, All Saints’ Day and All Souls’ Day. The celebration honored saints, martyrs and the dead. During the festival, turnips were carved into jack-o’-lanterns.

European immigrants brought Halloween traditions to America. Irish “mumming” and German “belsnickling” involved dressing in costume and going house to house in return for treats. Americans began using pumpkins instead of turnips for jack-o’-lanterns. The holiday became more about community and less about ghosts.

Trick-or-treating as we know it, when kids go door to door collecting candy, was established in American culture. Historians point to a “Peanuts” comic strip and a Disney cartoon featuring trick-or-treating in the 1950s to help pinpoint when the tradition took hold in America.