The minimum and maximum mass of protoneutron stars and neutron stars are investigated .
The hot dense matter is described by relativistic ( including hyperons ) and non-relativistic equations of state .
We show that the minimum mass ( \sim 0.88 - 1.28 M _ { \sun } ) of a neutron star is determined by the earliest stage of its evolution and is nearly unaffected by the presence of hyperons .
The maximum mass of a neutron star is limited by the protoneutron star or hot neutron star stage .
Further we find that the delayed collapse of a neutron star into a black hole during deleptonization is not only possible for equations of state with softening components , as for instance , hyperons , meson condensates etc. , but also for neutron stars with a pure nucleonic-leptonic equation of state .