Why does the spot of light from a laser pointer look grainy?

Question

Physics

I can't demonstrate in the photo, my phone does not convey exactly what the eye sees.
But the effect of graininess is easily visible to the naked eye on a surface illuminated by a scattered laser beam.
There is a feeling that the grain is static, if you do not change the angle of view. I would like to understand in detail the physics of this phenomenon.

Answer 1

https://en.wikipedia.org/wiki/Speckle_(interference)
In short, it is due to the interference of coherent laser light.