Various aspects of transport coefficients in quantum field theory are
reviewed. We describe recent progress in the calculation of transport
coefficients in hot gauge theories using Kubo formulas, paying attention to the
fulfillment of Ward identities. We comment on why the color conductivity in hot
QCD is much simpler to compute than the electrical conductivity. The
nonperturbative extraction of transport coefficients from lattice QCD
calculations is briefly discussed.Comment: 15 pages with 9 eps figures. Combined invited talk by G.A. and poster
by J.M.M.R. presented at Strong and Electroweak Matter (SEWM 2002),
Heidelberg, Germany, 2-5 Oct 200