  In this conference proceeding, we review important theoretical developments
related to the production of strangeness in astrophysics. This includes its
effects in supernova explosions, neutron stars, and compact-star mergers. We
also discuss in detail how the presence of net strangeness affects the
deconfinement to quark matter, expected to take place at large densities and/or
temperatures. We conclude that a complete description of dense matter
containing hyperons and strange quarks is fundamental for the understanding of
modern high-energy astrophysics.
