This paper investigates the concept of box invariance for classes of hybrid and switched systems. After motivating and defining the notion, we present a concise summary of results on its characterization for single-domain dynamical systems. The notion is then extended to the case of hybrid and switched systems. We provide sufficient conditions for a hybrid or switched system to be box invariant. Models of many real systems, especially those drawn from biology, have been found to be box invariant. This paper illustrates the concept using a pharmacodynamic model of blood glucose metabolism.