It is used as an algorithm for verifying transactions and adding new blocks to the blockchain. It works in such a way that the miners in the blockchain network compete with each other to solve a complex computational operation first. These operations are difficult to solve even with the use of digital technology. However, once the operation is resolved, it is very easy to verify it. Therefore, as soon as one of the miners solves the given operation, he can send a new block together with the correct solution to the blockchain network, and after verifying the correctness of the solution, the new block is also accepted by other miners. The miner who found the first correct solution is rewarded. In this way, the network is protected from attacks, because changing blocks in a blockchain would require a lot of computing power and a lot of time, and network disruption would therefore be more costly than possible gain. The PoW (Proof of Work) problem is the need to use expensive computing hardware that has high power consumption.