Energy flow refers to the transfer of energy through a system, often illustrated in ecosystems. It begins with the sun, which provides energy to plants, known as producers, through the process of photosynthesis. These plants convert sunlight into chemical energy, forming the base of the food chain. As energy moves through the ecosystem, it is passed from producers to consumers, such as animals that eat plants. When these animals are consumed by other animals, known as secondary consumers, energy continues to flow. Eventually, energy is released back into the environment as heat, completing the cycle.