A chimney is a vertical structure that allows smoke and gases from a fireplace, stove, or furnace to escape into the atmosphere. It is typically made of brick, stone, or metal and is designed to create a draft that pulls air and combustion gases upward. Proper ventilation is essential for safety and efficiency in heating systems. Chimneys can vary in design and size, depending on the type of heating appliance they serve. They often include components like flues, which direct the flow of gases, and caps, which prevent rain and debris from entering. Regular maintenance is important to prevent blockages and ensure safe operation.