While celebrating Halloween for most Americans centers on cute costumes and candy, the origins of the annual holiday were more about darker spiritual themes.
Dating back more than 2,000 years, the origins of Halloween involved Europe's Celtic peoples celebrating their New Year's Day on Nov. 1, called Samhain, according to National Geographic.
The night before the holiday, on Samhain eve – what we call Halloween on Oct. 31 – the ancients believed spirits walked the Earth as they traveled to the afterlife. They also believed fairies, demons and other creatures were present.
Then, like now, costumes were a part of these celebrations. Experts believe the Celtics wore costumes to confuse spirits and avoid being possessed. They also wore masks or blackened their faces as a way to impersonate the dead, National Geographic reported.
Sacrificing animals to gods and gathering around bonfires were also part of the event.
Church leaders later sought to influence the holiday, with Pope Boniface IV in the 7th century decreeing Nov. 1 as All Saints' Day, or All Hallows' Day.
The holiday began changing somewhat in the 19th century, with less emphasis on religious connotations and a greater focus on secular themes and children, History.com reported.
The modern holiday has also been influenced by the Catholic Hallowmas period of All Saints' Day and All Souls' Day, and the Roman festival of Feralia, according to History.com.
Halloween arrived in America with European immigrants, especially during the 1800s. The oldest U.S. Halloween celebration is thought to be in Anoka, Minn., according to National Geographic.
Today Halloween is a big business. Some 148 million Americans are expected to celebrate Halloween this year and each spend on average just over $66 on the key ingredients of the holiday – costumes, candy and decorations. An estimated $5.8 billion total will be spent, up $1 billion from 2009.