Sorry to be so ignorant! I have heard that light is a type of electro-magnetic radiation but I was also under the apprehension that photons were particles of light. Is that latter assertion too loose? Are photons just one of the many kinds of particles and do they just show up when electro- magnetic radiation is created ? Also ,if there are different frequencies of EM radiation can they all be classed as some form of light? Or are they just some class of EM radiation?