Proof of Work
AdvancedProof of work is a method used by some blockchains to agree on which transactions are valid, in which participants called miners compete to solve difficult computational puzzles, and the winner adds the next block and earns a reward.
Public blockchains need a way for many independent computers to agree on a single history of transactions without trusting a central authority. Proof of work achieves this by making it costly to add blocks.
Miners use powerful computers to repeatedly guess a number that, combined with the block's data, produces a result meeting a difficulty target. The first to find a valid answer broadcasts the block, and others verify it easily. The miner receives newly created coins and transaction fees.
Bitcoin uses proof of work. To rewrite past transactions, an attacker would need to control more computing power than the rest of the network combined, which is extremely expensive.
The main criticism of proof of work is its very high energy use, since miners consume large amounts of electricity. It can also concentrate mining in places with cheap power and among large operators. These concerns led some blockchains, including Ethereum in 2022, to switch to proof of stake.
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