Sunlight is fundamental for sustaining all life on Earth. It is the primary source of energy for photosynthesis, the process by which green plants produce their own food and oxygen. This oxygen is vital for the respiration of most living organisms. Sunlight also provides warmth, keeping Earth's temperature within a habitable range. Furthermore, it drives the water cycle, evaporating water to form clouds and precipitation, which is essential for freshwater supply. Without sunlight, Earth would be a frozen, lifeless planet.