Random quantum circuits provide a natural framework for exploring quantum many-body physics and universality in out-of-equilibrium systems. They are useful for understanding the role of entanglement and quantum information in thermalization and quantum chaos, and they constitute a basic tool for the development of quantum processors. In particular, they are central to both the quest for quantum supremacy and to the more pragmatic notion of quantum utility through quantum benchmarking. In this talk, I will give a gentle introduction to random quantum circuits and discuss the characterization of unitary and non-unitary error accumulation, using the well-known (many body) quantum fidelity.