Proof Of Work

A Proof-of-Work (PoW) system (or protocol, or function) is a consensus mechanism. It deters denial of service attacks and other service abuses such as spam on a network by requiring some work from the service requester, usually meaning processing time by a computer. The concept was invented by Cynthia Dwork and Moni Naor as presented in a 1993 journal article.[1] The term "Proof of Work" or PoW was first coined and formalized in a 1999 paper by Markus Jakobsson and Ari Juels. A key feature of these schemes is their asymmetry: the work must be moderately hard (yet feasible) on the requester side but easy to check for the service provider... Proof-of-work systems are being used as a primitive by other more complex cryptographic systems such as bitcoin which uses a system similar to Hashcash. https://en.wikipedia.org/wiki/Proof_of_work