◈ GLOSSARY · CRYPTO & WEB3
Proof of Work.
A definition, in plain English — with the books that teach it.
Reviewed by ClearValue Editorial Team · Jun 27, 2026
◈ DEFINITION
What it means
Definition
The consensus mechanism Bitcoin uses to decide who gets to write the next block: miners compete to find a number that, when hashed with the block, produces an output below a target. It's deliberately wasteful — the energy spent is the security. The honest caveat: PoW is battle-tested but energy-intensive, which is why most newer chains have moved to proof-of-stake; the trade-off is a different security model, not a free lunch.
◈ IN PRACTICE
Example
Bitcoin's network currently runs at roughly 600 exahashes per second — more computation per second than all the world's supercomputers combined. That's the wall an attacker would need to outspend to rewrite history.
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