The black hole is called the black hole because even the light cannot be released, the space is so dense that the particles with the fastest movement cannot escape.

According to the German physicist Schwarzschild, mass can be compressed to an infinitesimally small point, causing space-time bending, so nothing, even massless light photons, can escape from this bending. (schwarzschild metric)

Theoretically, all masses have a schwarzschild radius that can be calculated. If the mass of the sun were compressed to an infinitesimal point, it would probably form a black hole with a radius of just under 3 kilometers.