  A review is given on some recent developments in the theory of the Ising
model in a random field. This model is a good representation of a large number
of impure materials. After a short repetition of earlier arguments, which prove
the absence of ferromagnetic order in $d\le 2$ space dimensions for
uncorrelated random fields, we consider different random field correlations and
in particular the generation of uncorrelated from anti-correlated random fields
by thermal fluctuations. In discussing the phase transition, we consider the
transition to be characterized by a divergent correlation length and compare
the critical exponents obtained from various methods (real space RNG, Monte
Carlo calculations, weighted mean field theory etc.). The ferromagnetic
transition is believed to be preceded by a spin glass transition which
manifests itself by replica symmetry breaking. In the discussion of dynamical
properties, we concentrate mainly on the zero temperature depinning transition
of a domain wall, which represents a critical point far from equilibrium with
new scaling relations and critical exponents.
