Light has a dual “character” it sometimes behaves like a wave and sometimes like a particle. This is called “wave-particle” duality. We are aware of light reflecting, refracting, diffracting, etc and all these are wave properties of light However, high frequency ultraviolet light shows particle properties because when it is incident on certain metals, ultraviolet behaves like a stream of “particles” or quanta which interact 1 on 1 with electrons which are then knocked out and released.
