Question

what are photons and how are they related to light and why do they have 0 mass ?????

Answer 1

But according to special relativity, light ALWAYS travels with the light speed c, and is NEVER at rest. And so it has zero REST mass. which means that though photons don't have rest mass, they do have energy and thus they have mass. The photons are wave particles.:

Answer 2

a particle representing a light or other electromagnetic radiation. A photon carries energy proportional to the radiation frequency but has zero rest mass.