A Will-O'-The-Wisp is a phenomenon often seen in marshy or swampy areas, where small, flickering lights appear at night. These lights are typically blue or green and are caused by the combustion of gases released from decaying organic matter. People have historically associated these lights with supernatural beings or spirits, leading to various myths and legends. In scientific terms, the lights are known as ignis fatuus, which translates to "foolish fire." They can mislead travelers, causing them to wander off paths or into dangerous areas. While they are intriguing, Will-O'-The-Wisps are a natural occurrence rather than a mystical entity.