It has been celebrated for over 2000 years as pagan traditions.
Wearing masks comes from the Welsh and Celtic traditions that the dead visit the living on that day.
During the 1800s in America, the end of harvest was celebrated by wearing costumes, eating sweets, and playing tricks on each other.
Jack O' Lanterns started out in Ireland as hollowed out turnips with candles in them to ward off evil spirits.
Ninety nine percent of pumpkins are sold for Halloween for carving.
Orange and black are the traditional colors, because they represent the harvest and evil.
If you see a spider on Halloween, it is said to be the spirit of a loved one watching over you.
Eighty six percent of Americans decorate their house for Halloween, but the number is dwindling.
Halloween costume sales reached six billion dollars in 2009. Adults were 62% of that number.
About two billion dollars is spent on Halloween candy, annually.