It is an interesting possibility that dark matter particles are bound states of a strongly interacting dark sector that couples only weakly to the Standard Model. I will present the fundamental requirements on such dark sectors and discuss how they can be cosmologically viable and reproduce the observed dark matter abundance. Relevant constraints arise from direct detection experiments and bounds on dark matter self-interactions. At the LHC, the model gives rise to dark showers, which lead to a range of interesting signatures, such as broad resonances, semi-visible jets and displaced vertices. I will summarize existing constraints and give an overview over ongoing efforts to probe new regions of parameter space.