  The majority of the matter in the universe is still unidentified and under
investigation by both direct and indirect means. Many experiments searching for
the recoil of dark-matter particles off target nuclei in underground
laboratories have established increasingly strong constraints on the mass and
scattering cross sections of weakly interacting particles, and some have even
seen hints at a possible signal. Other experiments search for a possible mixing
of photons with light scalar or pseudo-scalar particles that could also
constitute dark matter. Furthermore, annihilation or decay of dark matter can
contribute to charged cosmic rays, photons at all energies, and neutrinos. Many
existing and future ground-based and satellite experiments are sensitive to
such signals. Finally, data from the Large Hadron Collider at CERN are
scrutinized for missing energy as a signature of new weakly interacting
particles that may be related to dark matter. In this review article we
summarize the status of the field with an emphasis on the complementarity
between direct detection in dedicated laboratory experiments, indirect
detection in the cosmic radiation, and searches at particle accelerators.
