  The lecture provides an introduction to thermal field theory and its
applications to the physics of the quark-gluon plasma, possibly created in
relativistic heavy ion collisions. In particular the Hard Thermal Loop
resummation technique, providing a consistent perturbative description of
relativistic, high-temperature plasmas is introduced. Using this method
interesting quantities of the quark-gluon plasma (damping rates, energy loss,
photon and dilepton production) are discussed. Furthermore recent developments
on non-equilibrium field theory, which are relevant for high-energy heavy ion
physics, are presented.
