  Neutron stars were first posited in the early thirties, and discovered as
pulsars in late sixties; however, only recently are we beginning to understand
the matter they contain. This talk describes the continuing development of a
consistent picture of the liquid interiors of neutron stars, driven by four
advances: observations of two heavy neutron stars with masses $\simeq$ 2.0
solar masses; inferences of masses and radii simultaneously for an increasing
number of neutron stars in low mass X-ray binaries, and future determinations
via the NICER observatory; the observation of the binary neutron star merger,
GW170817, through gravitational waves as well as across the electromagnetic
spectrum; and an emerging understanding in QCD of how nuclear matter can turn
into deconfined quark matter in the interior. We describe the modern
quark-hadron crossover equation of state, QHC18, and the corresponding neutron
stars, which agree well with current observations.
