Pumpkin, Pumpkin, Smiling Bright:
One of the most enduring symbols of Halloween is the jack o'lantern. Carved pumpkins are a mainstay of the Samhain season, and for some folks, the more elaborate the carved design, the better! A jack o'lantern typically holds a candle (you can also get battery-powered tealights, which are a lot safer) which illuminates the carved out design. School children are alternately delighted and terrified by them -- but how did the whole idea of carving up a pumpkin evolve in the first place?
The Turnip Issue:
Some scholars have claimed that the idea of a hollowed-out vegetable with a candle in the middle originated with the Celts. However, the Celts didn't have pumpkins, which are a North American plant. They did have beets, turnips, and other root vegetables. Have you ever tried to hollow out a raw beet? It's quite an experience, believe me.
In addition, it's pretty unlikely that the Celts carved faces into their vegetables. So the tradition of the jack o'lantern is a fairly modern invention, by historical standards, although no one has been able to figure out exactly when it began.
As mentioned, the pumpkin is a vegetable known primarily to North Americans. The native tribes here used it as a source of food for years before white men even set foot on their soil.
The first example of the jack o'lantern appearing in American literature is in an 1837 story by Nathaniel Hawthorne, who wrote The Scarlet Letter. The carved lantern didn't become associated with Halloween until around the time of the Civil War.
The Jack Story:
In many cultures, there exist what is known as a "Jack story". These are basically a series of folktales that revolve around a character -- Tricky Jack, Clever Jack, etc. -- and usually start off with Jack getting in some sort of trouble. They always end with Jack resolving his problem, often at his own expense -- in other words, a Jack Story is a typical cautionary tale. You can find these types of tales around the world, from Germany to the Scottish Highlands to the hills of Appalachia.
In the case of the jack o'lantern, the story that inspired it is one in which Jack tries to outsmart the Devil himself. In the tale, Jack tricks the Devil into agreeing never to collect his soul. However, once Jack dies, it turns out he's led too sinful a life to get into heaven, but because of his bargain with the Devil, he can't get into hell either. Jack complains about how dark it is, wandering around earth with no place to go, and someone tosses him a hot coal, which he places in a hollowed-out turnip. Now poor Jack uses his turnip-lantern to guide him, and he is known as Jack of the Lantern.
In some variations of the story, Jack comes out only on Halloween night, and is looking for someone to take his place... so watch out, if you see him wandering your way!