BlockchainIntermediate#Consensus#Security
Proof of Work (PoW)
P
Definition
A consensus approach in which a candidate block must demonstrate hashing work below a network target before nodes can accept it if all other consensus rules are met. Its security, energy use, and attack costs are network- and time-specific.
Source reviewed
- Bitcoin Developer Guide: Block Chain opens in a new tab
Supports: Documents Bitcoin proof-of-work targets, node validation, historical modification costs, and majority-hash-power limits.
- Bitcoin Developer Guide: Mining opens in a new tab
Supports: Documents Bitcoin mining target thresholds and the current solo/pool mining workflow; it is not a profitability forecast.
Concept Diagram
Key Takeaways
1
PoW block acceptance requires proof of work and all other network consensus rules
2
History-revision risk is probabilistic and depends on a specific network's hash power and conditions
3
Majority hash power cannot bypass every validation or ownership rule
4
Energy, mining economics, security, and censorship assumptions are not universal investment claims
Practical Example
When assessing a PoW network, a user checks the current consensus rules, mining and pool concentration, client diversity, confirmations or finality model, and current operational conditions. They do not infer security or an investment outcome from an old hashrate or energy statistic.
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Related Terms
Blockchain
ASIC (Application-Specific Integrated Circuit)Special-purpose hardware designed to perform a narrow computation efficiently. In proof-of-work mining, an ASIC is normally built for a particular hashing algorithm; it cannot be assumed to work for every network or remain profitable.
Blockchain
Consensus MechanismThe protocols, incentives, and rules that let distributed network participants select and validate a shared ledger state despite delays, faults, or conflicting proposals.
Blockchain
MiningIn a proof-of-work system, the process of building candidate blocks and repeatedly hashing their headers until one meets the network target. A valid block is still accepted only if it follows the network's consensus rules.
Blockchain
Proof of Stake (PoS)A family of consensus designs in which validators commit stake under network-specific rules and use it to participate in block proposal, attestation, or finality. Validator selection, rewards, penalties, delegation, and withdrawal rules vary by network.
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