Sunlight is energy radiated from the sun. It is created when nuclear fusion in the sun turns hydrogen into helium. The light can be divided into visible light, ultraviolet radiation, and infrared radiation, with the visible and infrared portions accounting for almost half of the total energy radiated, with ultraviolet accounting for only a very small proportion.
Some of the sunlight reaches Earth, passing through the atmosphere where some of the energy is absorbed, reduced, and scattered. Of the sunlight that reaches the surface, some of it is used by producers as an energy source for photosynthesis.