  Numerical simulations of quantum chromodynamics at nonzero temperature
provide information from first principles about the physical properties of the
quark gluon plasma. Because the lattice approximation can be refined
indefinitely, results of lattice simulations now provide the most reliable
basis for our understanding of the nonperturbative characteristics of the
plasma and of the high temperature phase transition. Following a brief overview
of the methodology of lattice gauge theory at nonzero temperature, recent
results and insights from lattice simulations are discussed. These include our
understanding of the phase diagram of QCD, the nature of the phase transition,
and the structure of the plasma.
