Recent measurements show that dark matter and dark energy yield 95% of the energy content of the Universe. Despite the extensive experimental effort, the nature, properties and origin of this dark sector remain concealed. The current paradigm portrays dark matter as a relic density of weakly interacting massive particles. Whereas the planned next generation dark matter direct and indirect detection experiments, as well as the LHC, may still validate this picture, it is necessary to prepare for possible different outcomes. In this new perspective, the dark sector may potentially be as complicated as the visible sector, consisting of different types of particles and governed by nontrivial dark interactions. This CER aims to explore the consequences of an interacting dark sector considering both conventional and nonconventional models of new physics, and studying its possible experimental signatures within particle physics, astroparticle physics and cosmology in an exhaustive way.