Quantum computing is a type of computation that harnesses the collective properties of quantum states, such as superposition, interference, and entanglement, to perform calculations. The devices that perform quantum computations are known as quantum computers.
By performing local measurements on systems, special correlation can be obtained. Such correlations can not be characterized by local hidden variable model, which are named as non-local correlation. It can be detected by Bell inequality. In short, if some given correlations that can not be produced by classical methods, they are non-local.