(CNN) -- Here is a look at what you need to know about Halloween, celebrated annually in the United States on October 31. In 2014, Halloween will fall on a Friday.
Facts: The word Halloween is an abbreviated version of the phrases All Hallows' Eve or All Hallows' Evening.
Halloween comes from an ancient pagan festival celebrated by Celtic people over 2,000 years ago called Samhain (prono: SOW ehn).
The festival took place in the United Kingdom, Ireland, and northwestern France.
Samhain means "summer's end" and marks the beginning of winter. Samhain is also thought to celebrate the beginning of the Celtic year. The Celts believed that Samhain was a time when the dead could walk among the living.
Trick-or-treating began in areas of the United Kingdom and Ireland. People went house-to-house "souling" - asking for small breads called "soul cakes" in exchange for prayer.
Adults also went door-to-door asking for food and drinks in exchange for a song or dance.
Jack-o'-lanterns are the symbol of Halloween. People in Ireland and Scotland originally used beets or turnips as lanterns on Halloween.
An Irish legend says that jack-o'-lanterns are named for a man called Jack who could not go to heaven or hell and was forced to walk the earth forever with only a coal from hell to light his lantern.
The name jack-o'-lantern can also be derived from the night watchman who would light the street lanterns every evening.
Immigrants from Ireland and Scotland brought Halloween to the United States in the 1800s. Haitian and African immigrants brought voodoo beliefs about black cats, fire, and witchcraft.
Halloween Statistics for 2013: (ALL from the National Retail Federation) Spending in the United States this year is estimated to reach $6.9 billion, down from 2012's $8 billion.
47.5% will decorate their home or yard, and 43.6% will wear a costume.
13.8% will dress up their pets.
Top Children's Costumes for 2013 1 Princess - 8.2% - 3,815,104 2 Animal - 6.1% - 2,819,860 3 Batman - 5.4% - 2,488,111 4 Action/Super Hero - 5.1% - 2,363,706 5 Spider-Man - 3.9% - 1,824,615
Top Adult Costumes for 2013 1 Witch - 9.6% - 5,141,241 2 Batman - 5.4% - 2,920,225 3 Vampire - 5.0% - 2,714,575 4 Zombie - 4.4% - 2,344,406 5 Pirate - 3.8% - 2,056,497
Top Pet Costumes for 2013 1 Pumpkin - 7.9% 2 Hot Dog - 6.9% T3 Cat - 4.8% T3 Devil - 4.8% 4 Witch - 4.2% 5 Superman 3.4%