The primary source of energy for photosynthesis is sunlight. This process, essential for life on Earth, occurs in the chloroplasts of plant cells, where light energy is converted into chemical energy. During photosynthesis, plants absorb sunlight and use it to convert carbon dioxide from the atmosphere and water from the soil into glucose and oxygen. Glucose serves as an energy source for the plant, while oxygen is released into the atmosphere, benefiting living organisms. This intricate process underlies the foundation of most ecosystems, as it not only produces food for plants but also supports the entire food chain through the energy captured from sunlight.