  This is the theory summary of Strangeness in Quark Matter 2019 conference.
Results include the state-of-the-art updates to the Quantum Chromodynamics
(QCD) phase diagram with contributions both from heavy-ion collisions and
nuclear astrophysics, studies on the QCD freeze-out lines, and several aspects
regarding small systems including collectivity, heavy flavor dynamics,
strangeness, and hard probes.
