The PoW is an underlying consensus protocol of different types of cryptocurrency of blockchain technology. The PoW describes a blockchain system that requires significant effort to perform the mining process. Thus, it prevents malicious exploitation of users computing power and various kinds of attacks on the system. It selects the next miners based on the computing power. Some of the applications of PoW are as follows.
   •  Litecoin
   •  Ethereum
   •  Bitcoin cash
   •  Zcash
  The advantages of PoW consensus are as follows.
   •  Quick consensus reachability
   •  Most battle-tested
   •  Deter Spammers
  The disadvantages of PoW are as follows.
   •  Huge amount of electricity dependency
   •  High resource wastage
   •  Need of centralization
   •  Less secure under small-scale networks
   •  Most vulnerable to 51% of attack