Proof of Work

In a sentence

Bitcoin uses proof of work to determine which miner may add the next block.

• Bitcoin uses proof of work to determine which miner may add the next block.
• Miners consumed computing power while searching for a hash that satisfied the proof-of-work target.
• Nodes could verify the completed proof of work much faster than miners could produce it.
• The difficulty adjustment kept proof-of-work block production near the target schedule.
• An attacker would need substantial hash power to rewrite recent proof-of-work history.