Q. Explain what is light?

Light is certainly electromagnetic radiation but the expression electromagnetic radiation is by no means an explanation of what light is. Light is a wave that which is "waving" (varying in a repetitive fashion in both time and space) is an electric field and a magnetic field. Light isn't matter. An electric field isn't matter. A magnetic field isn't matter. Light contains of both electric and magnetic fields that vary in both time and space in a regular repetitive matter. Since electric and magnetic fields aren't matter light can't be matter. Since light isn't matter, it can't consist of and doesn't consist of charged particles. Vacillate charged particles do cause light but they themselves are not light.