Tensor networks provide a new paradigm for describing quantum many body systems. Since the early years of quantum mechanics, the quantum many body problem has been one of the main driving forces in theoretical physics. In recent years, a lot of progress has been made in unraveling the entanglement structure of correlated systems, which resulted in the study of quantum tensor networks which model the entanglement degrees by local tensors. This had led to the development of new numerical methods for simulating complex quantum systems and of new analytic tools for classifying entangled and topological phases of matter. The aim of the school is to teach young PhD students the basics of tensor-product states as well as the most recent technical developments. This is particularly important given the increasing number of groups working on this quickly evolving topic. The lectures will be given by researchers who work actively both on the development and the application of tensor-product state based methods.