A proof-of-work (PoW) system (or protocol or function) is an economic measure to deter DOS attacks and other abuses (e.g., spam) on a network by requiring some work from the service requester, usually meaning processing time.
"La minería es la respuesta al Sybil attack. Es simple pero brillante. Esto es lo que diferencía una blockchain de cualquier otro sistema de cómputo. Es resistente a Sybil attacks."