  Theoretical models of the equation of state (EOS) of neutron-star matter
(starting with the crust and ending at the densest region of the stellar core)
are reviewed. Apart from a broad set of baryonic EOSs, strange quark matter,
and even more exotic (abnormal and Q-matter) EOSs are considered. Results of
calculations of M_max for non-rotating neutron stars and exotic compact stars
are reviewed, with particular emphasis on the dependence on the dense-matter
EOS. Rapid rotation increases M_max, and this effect is studied for both
neutron stars and exotic stars. Theoretical results are then confronted with
measurements of masses of neutron stars in binaries, and the consequences of
such a confrontation and their possible impact on the theory of dense matter
are discussed.
