Lattice Constraints on the QCD Chiral Phase Transition at Finite Temperature and Baryon Density

The thermal restoration of chiral symmetry in QCD is known to proceed by an analytic crossover, which widely expected turn into a phase transition with critical endpoint as the baryon density increased. In absence genuine solution sign problem lattice QCD, simulations at zero and imaginary chemical potential parameter space enlarged variable number quark flavours masses constitute viable way constrain location possible non-analytic its endpoint. this article I review recent progress towards understanding nature massless limit, temperature density. Combined increasingly detailed studies physical crossover region, current data bound point $\mu_B > 3T$.