what is proof of work pow 
proof of work pow is a blockchain consensus mechanism that requires significant computing effort from a network of devices the concept was adapted from digital tokens by hal finney in 2004 through the idea of reusable proof of work using the 160 bit secure hash algorithm 1 sha 1 1following its introduction in 2009 bitcoin became the first widely adopted application of finney s pow idea finney was also the recipient of the first bitcoin transaction proof of work is also the mechanic used in many other cryptocurrencies understanding proof of workproof of work is a concept used in some public blockchains to demonstrate that a program did the work required to propose a new block for the chain it is commonly called a consensus mechanism because eventually network consensus is reached after there is proof the work was done honestly in this case honestly means there were no attempts to alter data proof of work is provided by sending the information in a block through a hashing algorithm then adjusting variable fields until a hexadecimal number is reached that has a lower value than the network s difficulty target this serves as proof that the program expended the computational effort to hash the block until a solution was reached proof of work and consensushere s a quick rundown of the proof of work process on the bitcoin blockchain first the worker which is called a miner creates a temporary file a block if it wins the competition to solve for a winning hash this file will be stored on the blockchain the block has the four following fields the block header contains the following fields the mining program assembles this block and places the transactions it has prioritized in the transaction field it continuously adjusts the nonce and the extra nonce which is part of the coinbase transaction in the merkle tree and sends the information in the block through a hashing algorithm it repeats this process until it finds a solution which is a value less than or equal to the difficulty target the difficulty target is set so that a certain number of hashes per second must be attempted before a solution is found for example on may 17 2024 block 843 900 had a difficulty target of 83 148t or 83 148 trillion attempts per second per miner the winning hash for that block was 000000000000000000033028b3c8296ed776653032030cd01290f4345f5a9b6ethis hash provided proof to the network that the miner did the work the block was added to the blockchain and the network began its process of reaching consensus consensus the attribute most commonly associated with blockchain proofs is reached after the block is closed and added to the chain while working on proposing new blocks and generating winning hashes each miner also validates each new block as it is added each miner broadcasts to the network that the block it confirmed is valid new blocks use the previous block s header hash creating a chain of proof which leads to network consensus this is why these proofs are called consensus mechanisms because they form the basis of how consensus is reached proof of work vs proof of stakethe two most popular consensus mechanisms are proof of work and proof of stake bitcoin s top competitor ethereum used proof of work on its blockchain until september 2022 when its highly anticipated transition to proof of stake was made here are some of the key differences between the two validation is done by a network of minersbitcoin paid as a reward and for transaction feescompetitive nature uses lots of energy and computational powervalidation is done by participants who offer ether as collateralether is paid for transaction fees onlyless computational power and energy usedconsensus is reached faster because there is no difficultyspecial considerationsproof of work mining is a competitive process with many participants hoping for a profitable outcome because minable cryptocurrency has market value businesses have emerged and overtaken most of the computational power used by proof of work blockchains for example on may 17 2024 foundrydigital had the most hashing power on the bitcoin network 175 exa hashes per second eh s out of a network total of 673 eh s 2 foundry digital is owned by digital currency group a venture firm that has funded or invested in hundreds of cryptocurrency projects 3bitcoin and other cryptocurrencies that use proof of work were designed to be used and hosted by individuals for their benefit however individuals have been pushed out of the processes by businesses that have centralized them for profit 