// GLOSSARY -- BLOCKCHAIN & CRYPTO FUNDAMENTALS

What is Proof of Work (PoW)?

1 min read Updated

Proof of Work (PoW) is a consensus mechanism where miners compete to solve computationally intensive puzzles, earning the right to add the next block and receive rewards — securing the network through energy expenditure.

WHY IT MATTERS

PoW was Bitcoin's solution to the double-spend problem. Miners expend energy to find a hash meeting the difficulty target. This makes block creation expensive, which makes attacking the network prohibitively costly.

The elegance: PoW converts physical energy into digital security. To rewrite history, an attacker would need to outpace the entire network's hash rate — billions in hardware and electricity.

The criticism: enormous energy consumption. Bitcoin rivals small countries. This drove Ethereum's switch to PoS. PoW supporters argue the energy is the security guarantee itself.

FREQUENTLY ASKED QUESTIONS

How much energy does PoW use?
Bitcoin consumes roughly 100-150 TWh annually — comparable to a small country. This is both the cost and source of its security.
What is a 51% attack?
If an entity controls >50% of mining power, they could rewrite recent blocks. In practice, this is economically irrational for major chains — the attack cost exceeds potential gain.
Why did Ethereum leave PoW?
To reduce energy consumption by ~99.95%, enable faster finality, and lay groundwork for sharding. The Merge completed September 2022.

FURTHER READING

Enforce policies on every tool call

Intercept is the open-source MCP proxy that enforces YAML policies on AI agent tool calls. No code changes needed.

npx -y @policylayer/intercept
github.com/policylayer/intercept →
// GET IN TOUCH

Have a question or want to learn more? Send us a message.

Message sent.

We'll get back to you soon.