I briefly review our current understanding of the phase diagram of strongly interacting (QCD) matter in the temperature-baryochemical potential (or baryon density) plane. I discuss properties of the chiral/deconfinement transition of QCD. I focus on results from first-principles lattice QCD simulations. I also briefly mention connections with other approaches, such as heavy ion collision experiments. I also briefly discuss the chiral transition as a
function of the quark masses and how it is related to thermodynamics
at a non-zero chemical potential.