Halloween has its roots in the Christian holiday of All Saint’s Day and the Celtic festival of Samhaim. All Saint’s Day once called Old Hallows or Hallomass is celebrated on November 1. As the name states, it is a day to commemorate all those who have achieved Sainthood in Heaven. Samhaim is a celebration of summer’s end. The ancient Celts believed the border between this world and the “other world” becomes thin at this time of year allowing spirits to pass into our world. They believed in order to ward off these spirits, they would have to wear masks to disguise themselves. The actual word Halloween shows up in Scotland during the 16th century as a variant of All- Hallows-Even, the night before All Hallows Eve.
The famous Jack-o-Lantern got its start as the practice of commemorating the souls in purgatory with candle lanterns carved from turnips. In Celtic festivals, the turnips were carved with faces and placed in windows to ward off evil spirits. We use pumpkins here in the North America because they are plentiful and easier to carve then turnips!
Trick or Treating, the practice of dressing up in costume and going door to door begging for treats (or else!) dates back to the Middle Ages, when poor people would go door to door on Hallowmas, getting for in return for prayers for the dead. Trick or Treating as we know it, didn’t make any type of official presence in the US until 1934.
All of this celebrating and/or fearing of the dead, wearing costumes, begging for food eventually found its way to our modern Halloween celebration. If you want to read some more on the history and traditions of Halloween there are some great websites to visit: