A solar cooker is a device that uses the energy of direct sunlight to heat, cook or pasteurize food or drink. The vast majority of solar cookers currently in use are relatively inexpensive, low-tech devices. Because they use no fuel and cost nothing to operate, many nonprofit organizations are promoting their use worldwide in order to help reduce fuel costs and air pollution, and to help slow down the deforestation and desertification that are caused by gathering firewood for cooking.