Perhaps the most peculiar holiday on the American calendar, Halloween is an occasion that is steeped (fittingly enough) in mystery. It's one of our country's most popular holidays, with many people participating in trick-or-treating, donning costumes, eating candy, going to haunted houses, telling ghost stories, putting up spooky decorations and going to parties. Yet despite its popularity, the history of the holiday isn't often understood among the general population today.