The primary energy source of all living organisms is sunlight, which is harnessed through the process of photosynthesis. In plants, algae, and some bacteria, sunlight is absorbed by chlorophyll and converted into chemical energy stored in glucose. This process not only produces food for the organisms themselves but also generates oxygen as a byproduct, which is essential for the survival of aerobic life forms. In turn, animals and other consumers obtain energy by consuming plants or other organisms, following the food chain that depends significantly on the energy provided by sunlight.