21MERIDIAN 2140
83 / 104HC

Hashcash

Adam Back’s reusable proof-of-work concept, cited by the Bitcoin whitepaper.

Adam Back’s reusable proof-of-work concept, cited by the Bitcoin whitepaper.

Adam Back’s reusable proof-of-work concept, cited by the Bitcoin whitepaper. This coordinate is placed in the wider system through its protocol, economic and historical relationships.

Understanding Hashcash helps distinguish a verifiable Bitcoin mechanism or historical record from slogans, products and market narratives.

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Linked to related atlas coordinates

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Grounded in a source record

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Explains function and trade-offs

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Part of the open Bitcoin knowledge graph

DOC · 001HashcashPrimary
Reviewed 25 July 2026Source-first · No investment advice