A cold critical point of QCD

I briefly review some developments in lattice gauge theory that help us to build a more complete picture of the QCD phase diagram in the space of temperature T, baryon chemical potential $\mu_B$, and electric charge $\mu_Q$. A simple analysis leads us to believe that the critical point of QCD, which is sought in the RHIC beam energy scan, develops into a critical line. This line ends at zero temperature, implying that cold dense matter has a critical point for the transition between hadron and quark phases. The critical indices are Ising-like, but the location of this point is currently uncertain.