Bell’s theorem proves the existence of quantum correlations, often known as Bell nonlocal, that cannot be described by classical theories, in which measurement outcomes are predetermined. In recent years, Bell nonlocal correlations have also acquired the status of information resource, as they are crucial for the construction of quantum information protocols in the device-independent scenario, where no modelling of the devices is assumed in the implementation. Because of this absence of modelling, device-independent protocols offer the strongest form of security attainable in quantum theory. This seminar provides an introduction to all these concepts, going from quantum foundations to quantum information science and back. The main ideas and tools in the device-independent formalism are explained, together with an overview of the main results and remaining challenges.