A ghost is someone who died but whose spirit did not "move on" and who still haunts the Earth. Belief in ghosts is widespread and there are ghost stories from many different countries and cultures. However, the existence of ghosts has not be proven by science and there are usually simple and mundane explanations behind accounts of hauntings In fiction and folklore, ghosts may be always visible, always invisible, or able to make themselves either visible or invisible at will. In popular culture, ghosts are often depicted as being covered by white sheets. The sheets originally represented shrouds, in which the dead were wrapped before burial. Ghosts are sometimes depicted as being completely white or another pale color, from head to foot but otherwise looking like ordinary people. Similarly, ghosts are sometimes depicted as people who look quite normal except for the fact that they are transparent. Ghosts may even look exactly the same as living people, although possibly distinguished by strange or old-fashioned clothes, and only be revealed to be ghosts when they do something unusual, such as suddenly vanishing Ghosts are sometimes said to appear as they looked at the moment of their death. Consequently, people who died violently or in horrific accidents may appear to look especially frightening, having blood stains about them or appearing to be horribly deformed. There are many stories of headless ghosts, the spirits of people who died after they were beheaded. The Headless Horseman from Washington Irving's "The Legend of Sleepy Hollow" is a famous fictional example. Headless ghosts are often said to carry their heads beneath their arms. In Britain, there are many stories of phantom stage coaches which usually have both headless drivers and horses