The term jack o’lantern was first applied not to pumpkins, but people. In 1663, the term meant a man with a lantern, or a night watchman. Just a decade later, it began to be used to refer to the mysterious lights sometimes seen at night over, swamps, and marshes.These ghost lights— called jack-o’-lanterns, hinkypunks, hobby lanterns, corpse candles, fairy lights, will-o'-the-wisps, and fool's fire—are created by gases from decomposing plant matter. For centuries before there was this scientific explanation, people told stories to explain the mysterious lights. In Ireland those stories often involved a guy named Jack.Stingy Jack, was a blacksmith who invited the Devil to join him for a drink. Stingy Jack didn't want to pay for the drinks from his own pocket, and convinced the Devil to turn himself into a coin that could be used to pay for the drinks. The Devil did so, but Jack didin't use the coin to pay the bill but kept the Devil-coin in his pocket with a silver cross so the Devil couldn’t turn back to his original form. Jack eventually let the Devil loose, but made him promise that he wouldn’t look for revenge on Jack, and wouldn’t claim his soul when he died.Later, Jack annoyed the Devil again by convincing him to climb up a tree to pick some fruit, and then carved a cross in the trunk so the Devil couldn’t climb back down (the Devil is, apparently, an idiot). Jack set him free again, on the condition that the Devil once again not take revenge and not claim Jack’s soul.When Stingy Jack died, God didn't allow him into Heaven, and the Devil, keeping his word, refused to accept Jack’s soul in Hell. Instead, the Devil gave him a single burning coal to light his way and sent him off into the night to “find his own Hell.” Jack put the coal into a carved turnip and has been roaming the Earth with it ever since. In Ireland people say that the ghost lights in the swamps are Jack’s improvised lantern moving around and he and the lights were named "Jack of the Lantern," or "Jack O'Lantern."