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.