One of the most prominent features of quantum physics is the existence of quantum correlations between different quantum systems, which are not equivalent to quantum entanglement. Although quantum entanglement has long been regarded as the primary manifestation of quantum correlations, Ollivier and Zurek introduced the concept of quantum discord in 2002, highlighting that quantum correlations can also exist between subsystems in zero-entanglement systems. Unlike in classical information theory, the overall information of a quantum system cannot be simply described as the sum of the information of its subsystems. In this paper, we review the fundamental theory and calculation methods of quantum discord, with a particular focus on its applications in quantum information processing. In addition, we analyze the role of quantum discord in quantum teleportation, showing that quantum discord exhibits strong robustness against decoherence and noise, providing crucial resources for quantum information processing.