Photon, that is, light quantum, is the general term after light quantization.

Light is characterized by wave-particle duality. That is to say, there are both fluctuations and particles:

A) Properties of waves: Light can interfere with each other, and negotiation fringes between light and dark can be observed in the double-slit experiment.

B) particle properties: the energy unit of light is the smallest. At a certain frequency, the propagation of light can be regarded as the transfer of energy from one packet to another, and the energy in each packet is certain, so each of these discontinuous packets can be regarded as a particle.

Gravitational waves are ripples in space-time itself. Imagine that a piece of rope is tied to a post and the other end is swung up and down by you. You will observe that there is a "pulse" walking back and forth on the rope, which is a mechanical wave, that is, the "ripple" of the rope itself; Just as the waves on the sea are the ripples of the sea itself.

Just as waves on the sea hit you and you feel pushed by it, waves carry energy. Gravitational waves also carry energy, but the energy is weak.