  Astronomical and cosmological observations of the past 80 years build solid
evidence that atomic matter makes up only a small fraction of the matter in the
universe. The dominant fraction does not interact with electromagnetic
radiation, does not absorb or emit light and hence is called Dark Matter. So
far dark matter has revealed its existence only through gravitational effects.
The strongest experimental effort to find other evidence and learn more about
the nature of the dark matter particles concentrates around Weakly Interacting
Massive Particles which are among the best motivated dark matter candidates.
The two main groups of experiments in this field aim for indirect detection
through annihilation products and direct detection via interactions with atomic
matter respectively. The experimental sensitivity is starting to reach the
parameter range which is preferred by theoretical considerations and we can
expect to confirm or dismiss some of the most interesting theoretical models in
the next few years.
