A foghorn is a type of loud warning signal used to alert ships of nearby hazards or to indicate the presence of fog. It is typically a loud, low-frequency sound that can be heard over long distances and is used to warn ships of shallow water, rocks, and other potential hazards. The sound of a foghorn is distinct and recognizable, and is often associated with the ocean. Foghorns are typically used in areas with heavy fog or poor visibility, as they can be heard over long distances and are often the only warning a ship has of potential danger. The sound of a foghorn is often used in films and television shows to evoke a sense of mystery and danger, as well as a reminder of the ocean.