The shortest answer to the question. Photon is a quantum of light.
Such an answer contains a host of mysteries, the clarification of which requires penetration into the depths of modern quantum physics.
Even the question of how the concept of "photon" was formed is not so easy to answer. It was formed 125 years ago thanks to the works of J. Stoney and other outstanding physicists.
In its final form, this concept was formed thanks to the works of physicists - Lewis, Ehrengaft, Planck, Stony and others. Einstein and Newton can also be included in this list.
The photon has a dual nature - it is both a corpuscle and a wave.
The photon is moving in a strange way. This is the only elementary particle (that a photon is a particle, it follows from the corpuscular theory), which moves along a helical trajectory, describing a cycloid.
Thus, a photon is a toroidal vortex bunch of ether, which transfers energy when moving along a helical spiral trajectory.
And this vortex has special properties. It has been established that a photon is capable of knocking an electron out of an atom. Considering the ratio of the masses of these elementary particles, it looks as if a mosquito knocks down a huge elephant like a feather. It is impossible to believe in this, but you have to believe the scientists.
Promotional video:
And every science fiction lover is familiar with the phenomenon of the solar wind. The stream of photons creates pressure that can accelerate the spacecraft to near-light speed.
A photon appears at the moment an electron transitions from one orbit to another. In this case, a quantum of light is emitted, i.e. a photon. We live in a world of light, the light is always around us and even inside us - in the form of flashes in the eyes, which have been seen by many (especially the elderly). This means that photons are born every moment in incredibly huge quantities and rush at the speed of light in Space, telling everyone who is interested about how the Universe works.
Photon is elementary simple and mysterious, like the world around us. Warning everyone not to build illusions, Albert Einstein said: "… now every scoundrel thinks that he knows what a photon is, but he is mistaken …".