Verifiable computational work that orders valid Bitcoin history.
Proof of work meaning
Proof of work requires miners to find a block-header hash below a target. Finding one is deliberately costly and probabilistic; checking it is fast. This asymmetry lets nodes compare valid chains by accumulated work.
How it works in Bitcoin
Miners repeatedly change header inputs and hash candidate headers. Difficulty controls the target. Nodes first verify the block's rules and then account for its work; proof of work cannot turn an invalid block into a valid one.
A simple example
Rewriting a confirmed transaction would require rebuilding the work for its block and catching up with the valid chain as new blocks continue to arrive.
Why Proof of work matters
Mining terms connect proof of work, block production, incentives and energy. They should not be used as shorthand for node validation or guaranteed profitability.
What people often get wrong
Proof of work secures ordering and makes history expensive to alter. It does not protect a stolen seed phrase, prevent exchange fraud, or guarantee an asset price.
Quick checks before using the term
- Is this about hashrate, energy, revenue or validation?
- Which unit and period does the claim use?
- What changes when difficulty or fees move?
Apply these questions to the concrete example above. A precise answer is more useful than repeating the definition without naming the actor, rule or failure path.
Check the primary reference
This entry is written in plain English, but the technical source is available when you need exact protocol detail.
Bitcoin Developer Guide: Mining ↗