What is a gravitational collapse?

This would be the range of stars of a size range that maintains enough mass to bring a condensing contraction of the cooling star as it's nuclear fuel passes through the light elements until the fusion (sticking together as opposed to fission or splitting apart) is halted at the progression up the elemental chart at Fe or Iron and less energy is produced over a wider area as the Iron heart of the star builds providing less heat to keep the star expanded against its own mass... small stars with little mass tend to become brown dwarfs. Cinders almost. Stars with a bit more extra mass will fall in on themselves gaviticaly as their energy is expended until stopped by the physical forces that bind electrons (white dwarfs) and atomic nuclei (neutron stars) with the largest masses that don't go super nova massive are greater even than the electromagnetic forces binding atoms and the collapse is to a mathmatical singularity the famous black hole... but this picture is far to simple... for example the super massive black holes that seem to be associated with most galactic centers and there are timescale issues with large scale formations (apparent) but that's the idea in a nutshell