LATTICE QCD AT FINITE TEMPERATURE

We review lattice QCD investigations at high temperature. After a short introduction to thermal QCD on the lattice, we report on the present understanding of the phase diagram and the equation of state, particularly in the presence of dynamical quarks. We discuss various screening lengths in the plasma phase, including results from dimensionally reduced QCD. We then summarize lattice data on quark-number susceptibilities and spectral densities, both of which are immediately relevant to the interpretation of heavy-ion experiments. A major section is devoted to simulations of QCD at small, yet phenomenologically important, values for the baryon density.