  Gauge fixing is a useful tool to simplify calculations. It is also valuable
to combine different methods, in particular lattice and continuum methods.
However, beyond perturbation theory the Gribov-Singer ambiguity requires
further gauge conditions for a well-defined gauge-fixing prescription.
Different additional conditions can, in principle, lead to different results
for gauge-dependent correlation functions, as will be discussed for the example
of Landau gauge. Also the relation of lattice and continuum gauge fixing beyond
perturbation theory will be briefly outlined.
