  The infrared behaviour of the gluon and ghost propagators in Landau gauge QCD
is reviewed. The Kugo-Ojima confinement criterion and the Gribov-Zwanziger
horizon condition result from quite general properties of the ghost
Dyson-Schwinger equation. The numerical solutions for the gluon and ghost
propagators obtained from a truncated set of Dyson-Schwinger equations provide
an explicit example for the anticipated infrared behaviour. The results are in
good agreement with corresponding lattice data obtained recently. The resulting
running coupling approaches a fix point in the infrared, $\alpha(0) =
8.92/N_c$. Two different fits for the scale dependence of the running coupling
are given and discussed.
