It might seem that mainstream in Quantum Computing nowadays is completely focused on beating classical computers -quantum supremacy- in tasks with -quantum utility- or without practical applications. However, it might be instructive to recall that this area of research was born and developed mostly due to theoretical curiosity, namely from the exploration of fundamental properties of quantum mechanics, such as quantum entanglement. In this talk, after a general introduction on state-of-the-art quantum computers and simulators, I will present several examples of quantum simulators motivated only by their theoretical interest.