We analyze the phase diagram of QCD with two massless quark flavors in the space of temperature $T$ and chemical potential of the baryon charge \ensuremath{\mu} using available experimental knowledge of QCD, insights gained from various models, as well as general and model independent arguments including continuity, universality, and thermodynamic relations. A random matrix model is used to describe the chiral symmetry restoration phase transition at finite $T$ and \ensuremath{\mu}. In agreement with general arguments, this model predicts a tricritical point in the $T\ensuremath{\mu}$ plane. Certain critical properties at such a point are universal and can be relevant to heavy ion collision experiments.