The primary source of energy for living organisms is the sun. Through the process of photosynthesis, plants capture sunlight and convert it into chemical energy stored in glucose. This energy serves as the foundation of the food chain, supporting all life forms. Herbivores consume plants to obtain energy, while carnivores obtain energy by eating herbivores or other carnivores. Additionally, some organisms, like certain bacteria, utilize alternative sources, such as minerals or chemical reactions, to produce energy. Overall, solar energy is crucial for sustaining life on Earth.