  Hidden sectors in connection with GeV-scale dark forces and dark matter are
not only a common feature of physics beyond the Standard Model such as string
theory and SUSY but are also phenomenologically of great interest regarding
recent astrophysical observations. The hidden photon in particular is also
searched for and constrained by laboratory experiments, the current status of
which will be presented here. Furthermore, several models of hidden sectors
containing in addition a dark matter particle will be examined regarding their
consistency with the dark matter relic abundance and direct detection
experiments.
