The primary function of chloroplasts is to facilitate photosynthesis, converting light energy into chemical energy stored in glucose. These organelles contain chlorophyll, which captures sunlight and initiates the process of transforming carbon dioxide and water into oxygen and carbohydrates. Chloroplasts are crucial for plant growth and energy production, providing the necessary food source for almost all life forms on Earth. Their role in photosynthesis is foundational to the energy flow in ecosystems.