<Table> <Tr> <Td> </Td> <Td> This article may require cleanup to meet Wikipedia's quality standards . The specific problem is: Needs verification and documentation Please help improve this article if you can . (May 2015) (Learn how and when to remove this template message) </Td> </Tr> </Table> <Tr> <Td> </Td> <Td> This article may require cleanup to meet Wikipedia's quality standards . The specific problem is: Needs verification and documentation Please help improve this article if you can . (May 2015) (Learn how and when to remove this template message) </Td> </Tr> <P> A proof - of - work (PoW) system (or protocol, or function) is an economic measure to deter 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 . The term "Proof of Work" or POW was first coined and formalized in a 1999 paper by Markus Jakobsson and Ari Juels . An early example of the proof - of - work system used to give value to a currency is the shell money of the Solomon Islands . </P> <P> A key feature of these schemes is their asymmetry: the work must be moderately hard (but feasible) on the requester side but easy to check for the service provider . This idea is also known as a CPU cost function, client puzzle, computational puzzle or CPU pricing function . It is distinct from a CAPTCHA, which is intended for a human to solve quickly, rather than a computer . Proof of space (PoS) proposals apply the same principle by proving a dedicated amount of memory or disk space instead of CPU time . Proof of bandwidth approaches have been discussed in the context of cryptocurrency . Proof of ownership aims at proving that specific data are held by the prover . </P>

What is the point of proof of work