  A brief overview about our knowledge on galaxy cluster magnetic fields is
provided. Emphasize is given to the mutual dependence of our knowledge on
relativistic particles in galaxy clusters and the magnetic field strength.
Furthermore, we describe efforts to measure magnetic field strengths,
characteristic length-scales, and power-spectra with reliable accuracy. An
interpretation of these results in terms of non-helical dynamo theory is given.
If this interpretation turns out to be correct, the understanding of cluster
magnetic fields is directly connected to our understanding of intra-cluster
turbulence.
