Gravity collapses everything into a mathematical point.

All stars are "held up" against the inward pull of gravity
by radiation and pressure due to high temperature from
thermonuclear fusion going on in the star's core. When
all fusion creases, gravity wins

There are four (4) fates for the end of stars depending on
their masses and the masses of their cores:

Red/Brown Dwarfs - less than 0.6 Ms <== Main Sequence
0.01-0.8 Ms Stars less than about 0.6 solar masses, when
nuclear fuel is used up, gravitational collapse shrinks
the star, but no more than the gas temperature-pressure-volume
laws of classical physics allow. We have not found any white
dwarf less massive than 0.6 solar masses. Part of the answer
is that the universe may not be old enough for lower mass
stars to have evolved off the main sequence.

White Dwarfs - 0.6 and 1.4 Ms <== Main Sequence 0.8-10 Ms
Stars with core masses between 0.6 and 1.4 solar masses are
destined to become white dwarfs. White dwarfs are degenerate
matter.
Further collapse is halted by electron degeneracy pressure.
See pages 456-459 in your textbook. The vast majority of stars
are in this mass range and are destined to become white dwarfs

Neutron Stars - 1.4 and 2.9 Ms <== Main Sequence 10-30 Ms
Core masses between 1.4 and 2.9 solar masses overcome electron
degeneracy pressure and collapse to form neutron stars, a star
that is essentially one gigantic nucleus. Further collapse is
halted by neutron degeneracy pressure.

Black Holes - 3 or more Ms <== Main Sequence > 30 Ms
But for cores with mass of 3 or more solar masses, neutron
degeneracy pressure does not stop the collapse and the star
becomes a black hole with zero physical size, but with all
the mass. Gravity really wins!