Scientists call light electromagnetic radiation. There are many types of
light. But visible light is only a small portion of a family of light. the
important thing to know that both light and EM radiation carry energy. The
quantum theory suggests that light consists small bundles of energy/
particles. Scientists call those particles photons. A lot of photons give
bright and more intense light.
A light year is the distance that light travels in one through vacuum
or empty space.