Why are stars considered sources of energy?

Stars are considered sources of energy because they generate immense amounts of heat and light through nuclear fusion processes occurring in their cores. In these processes, hydrogen atoms fuse to form helium, releasing vast quantities of energy in the form of electromagnetic radiation, including visible light. This energy radiates outward, providing the heat and light that sustain life on planets like Earth. Additionally, stars contribute to the synthesis of heavier elements, further influencing the energy dynamics of the universe.