A proof-of-work (PoW) is a piece of data that is difficult (costly, time-consuming) to produce but easy for others to verify and that satisfies certain requirements. Producing a proof of work can be a random process with low probability so a lot of trial and error is required on average before a valid proof of work is generated.
A major advantage of PoW is its ability to safeguard against 51 percent attack. In order for an attacker to control more than half of the network’s computational power, it would cost him millions of dollars in mining equipment and electricity bills. It also protects against Sybil attacks, where an attacker can create multiple fake identities in order to gain control over the network. You can find dozens of open source libraries on the Internet these days. Below are the top 11 Python Proof of work libraries in use today: