  A brief survey is presented of our present understanding of the
equation-of-state of cold, dense matter and the speed of sound in the interior
of neutron stars, based on the constraints inferred from observational data.
The second part focuses on strangeness in baryonic matter and the role of
hyperon-nuclear two- and three-body forces, with reference to the "hyperon
puzzle" in neutron stars and possible scenarios for its solution.
