Halloween is thought to date back to Samhain, a Celtic New Year's Day that fell on November 1. Demons, fairies, and spirits of the dead were thought to walk the Earth the night before when the separation was thin between the worlds of the living and the dead. The Celts lit bonfires and set out gifts of food, hoping to win the favor of the spirits of those who had died in the past year. They also disguised themselves so the spirits of the dead wouldn't recognize them.  Samhain later transformed in the seventh century into All Saints' Day or All Hallows' Day as Christian leaders co-opted pagan holidays. But the night before continued to be observed with bonfires, costumes, and parades under the new name All Hallows' Eve-later "Halloween."                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          European immigrants then brought Halloween to the United States, and the celebration became popular in the 1800s, when Irish American immigration exploded. Their folk customs and beliefs merged with existing agricultural traditions, meaning Halloween dabbled in the occult, but stayed grounded in the fall harvest. Over the years, the holiday became a time for children to dress up as the ghosts their ancestors once feared. But how did these Celtic traditions evolve into one of children trick-or-treating in costumes for fun and candy--not for safety from spirits?     According to the fifth edition of Holiday Symbols and Customs, in as early as the 16th century, it was customary in England for those who were poor to go begging on All Souls' Day, and children eventually took over the custom. At the time, it was popular to give children cakes with crosses on top called "soul cakes"- in exchange for prayers on your behalf.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  Lisa Morton, author of Trick or Treat: A history of Halloween, traces one of the earliest mentions of typical Halloween celebrations to a letter from Queen Victoria about spending Halloween around a bonfire in Scotland in 1869. "Having named the circuit of the Castle," the letter said, "the remainder of the torches were thrown in a pile at the south-west corner, thus forming a large bonfire, which was speedily augmented with other combustibles until it formed a burning mass of huge proportions, round which dancing was spiritedly carried on."  Morton writes that people in the American middle class often were anxious to imitate their British cousins, which would explain a short story printed in 1870 that painted Halloween as an English holiday celebrated by children with fortune-telling and games to win treats. However, Morton writes that it's possible that trick-or-treating may be a more recent tradition that, surprisingly, may have been inspired by Christmas.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    A popular 18th- and 19th-century Christmas custom called 'belsnickling' in eastern areas of the U.S. and Canada was similar to trick-or-treating: Groups of costumed participants would go from house to house to perform small tricks in exchange for food and drink. Some belsnicklers even deliberately frightened young children at houses before asking if they had been good enough to earn a treat.  And other early descriptions say that those handing out treats had to guess the identities of the disguised revelers, giving food to anyone they couldn't identify.  In the 19th century, "tricks"--such as rattling windows and trying doors shut--were often made to look as though supernatural forces had conjured them.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        These pranks likely gave rise to the use of the phrase"trick or treat."  Barry Popik, an etymologist, traced the earliest usage of the phrase in connection with Halloween to a 1927 Alberta newspaper article reporting on pranksters demanding "trick or treat" at houses. Candy had first made its appearance in the 1800s at American Halloween parties as taffy that children could pull, and candy is now solidified as the go-to "treat." Since the rise of trick-or-treating after World War II, chocolate has reigned supreme as the most popular sweet to hand out. By 2009, Halloween has become the top U.S. holiday for chocolate sales, and that number keeps on growing.  The day has become the nation's second largest commercial holiday, and this year, Americans are expected to spend an estimated $3 billion on Halloween candy, according to the National Retail Federation. Reese's Peanut Butter Cups is America's most beloved Halloween candy. About 35 million pounds of candy corn is produced each year with the majority sold for halloween, according to the National Confectioners Association.