GLOSSARY // Crypto
Proof of Work
Proof of work is the method Bitcoin uses to agree on its ledger: miners race to solve a hard math puzzle, and the winner adds the next block and collects the reward. The puzzle is deliberately expensive to solve and trivial to check, which is what makes cheating uneconomic.
Security comes from that cost. To rewrite history an attacker would need to out-compute the entire honest network, which would take more electricity and hardware than the attack could ever pay off. The same energy use is the main criticism, and the reason many newer chains chose proof of stake instead.
The Bitcoin network's miners collectively perform hundreds of quintillion calculations per second. Redoing the work behind even a single recent block would require a share of that hardware no attacker can quietly assemble, which is why deep transactions are treated as final.
Related terms
Educational only — not financial advice. Definitions simplified for clarity; markets are messier than definitions.