Glossary · P
Proof of Work (PoW)
The original blockchain consensus mechanism used by Bitcoin. Miners compete to solve computationally intensive puzzles; the winner adds the next block and earns a reward. PoW is energy-intensive but extremely well-tested. Bitcoin, Litecoin, and Monero use Proof of Work.
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How Proof of Work works in practice
Proof of work secures a chain by requiring miners to expend computation. Rewriting history means redoing that work faster than the honest network, which is what makes the cost of attack physical and ongoing.
Worked example
Miners race to find a valid hash; the winner proposes the block. Attacking the chain requires acquiring a majority of that computational power and continuing to pay for it.
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The mistake that costs people money
Security scales with energy spent, which is both the strength and the criticism. Smaller proof-of-work chains with low hash rate have been successfully attacked — the model only protects what it costs enough to attack.
Proof of Work: common questions
- What is Proof of Work?
- The original blockchain consensus mechanism used by Bitcoin. Miners compete to solve computationally intensive puzzles; the winner adds the next block and earns a reward. PoW is energy-intensive but extremely well-tested. Bitcoin, Litecoin, and Monero use Proof of Work.
- How does Proof of Work work in practice?
- Proof of work secures a chain by requiring miners to expend computation. Rewriting history means redoing that work faster than the honest network, which is what makes the cost of attack physical and ongoing.
- Can you give an example of Proof of Work?
- Miners race to find a valid hash; the winner proposes the block. Attacking the chain requires acquiring a majority of that computational power and continuing to pay for it.
- What do people get wrong about Proof of Work?
- Security scales with energy spent, which is both the strength and the criticism. Smaller proof-of-work chains with low hash rate have been successfully attacked — the model only protects what it costs enough to attack.