Operation of stars

Stars operate through nuclear fusion, where immense pressure and temperature in their cores cause hydrogen atoms to combine into helium. This process releases a tremendous amount of energy in the form of light and heat, which radiates outward. The balance between gravitational force pulling inward and the outward pressure from fusion maintains the star's stability over most of its life. When the hydrogen runs out, the star's core contracts and heats up, leading to further fusion and new stages of evolution. Ultimately, stars end their lives as white dwarfs, neutron stars, or black holes, depending on their initial mass.