Heavy quark free energies, potentials and the renormalized Polyakov loop

We discuss the renormalized free energy of a heavy quark anti-quark pair in the color singlet channel for quenched and full QCD at finite temperature. The temperature and mass dependence, as well as its short distance behavior is analyzed. Using the free energies we calculate the heavy quark potential and entropy in quenched QCD. The asymptotic large distance behavior of the free energy is used to define the non-perturbatively renormalized Polyakov loop which is well behaved in the continuum limit. String breaking is studied in the color singlet channel in 2-flavor QCD.