Quantum steering is the phenomenon where one party (Alice) steers the quantum system of another party (Bob) into distinct ensembles of states by performing different measurements on her subsystem. It is known to be a type of nonlocality that is stronger than quantum entanglement, but weaker than Bell nonlocality. A notable characteristic that sets Einstein-Podolsky-Rosen steering (EPR-steering) apart from other types of nonlocality is its inherent asymmetry. In this thesis, we investigate the power of EPR-steering in a bipartite setting with one pure steered state, and multi-party networks with different configurations. There are three main parts. [...]