Blockchain
Also known as: 블록체인
A blockchain is a distributed ledger that records transactions in linked, cryptographically secured blocks maintained by a network of nodes.
Is blockchain the same as Bitcoin?
No. A blockchain is the underlying data structure: a shared ledger of hash-linked blocks that can only be added to. Bitcoin is one application built on it, a cryptocurrency whose white paper was published on 31 October 2008 and whose first block was mined on 3 January 2009. Other public blockchains, such as Ethereum, run smart contracts. Permissioned platforms such as Hyperledger Fabric are used by known groups of organisations and do not need a public cryptocurrency.
Key facts
| Predicate | Value | Source |
|---|---|---|
| Definition (NIST) | Tamper-evident and tamper-resistant digital ledgers implemented in a distributed fashion, without a central repositoryas of Oct 3, 2018 | [1]governmentIR 8202, Blockchain Technology OverviewNational Institute of Standards and Technology (NIST) |
| Central authority | Usually operates without a central authority such as a bank, company or governmentas of Oct 3, 2018 | [1]governmentIR 8202, Blockchain Technology OverviewNational Institute of Standards and Technology (NIST) |
| Immutability | Under normal network operation, no transaction can be changed once publishedas of Oct 3, 2018 | [1]governmentIR 8202, Blockchain Technology OverviewNational Institute of Standards and Technology (NIST) |
| US government reference document | NIST IR 8202, Blockchain Technology Overview (Yaga, Mell, Roby, Scarfone), DOI 10.6028/NIST.IR.8202as of Oct 3, 2018 | [1]governmentIR 8202, Blockchain Technology OverviewNational Institute of Standards and Technology (NIST) |
| Typical use | The underlying technology of cryptocurrency systemsas of Oct 3, 2018 | [2]governmentBlockchain Technology Overview: NIST Internal Report 8202 Now AvailableNational Institute of Standards and Technology (NIST) |
| Foundational paper | "Bitcoin: A Peer-to-Peer Electronic Cash System" by Satoshi Nakamoto (pseudonym) | [3]officialBitcoin: A Peer-to-Peer Electronic Cash SystemBitcoin Project (bitcoin.org) |
| Notable consensus change (official claim) | Ethereum mainnet moved from proof of work to proof of stake (the Merge)as of Sep 15, 2022 | [4]officialThe Mergeethereum.org |
| Ethereum energy reduction after the Merge (official claim) | About 99.95% (figure stated by the Ethereum project) percentas of Sep 15, 2022 | [4]officialThe Mergeethereum.org |
| South Korea: crypto-asset regulation | Act on the Protection of Virtual Asset Users in force; requires bank custody of user deposits, segregation of assets and monitoring for unfair tradingas of Jul 19, 2024 | [5]governmentAct on the Protection of Virtual Asset Users (press release)Financial Services Commission, Republic of Korea |
| South Korea: Act enacted | Act on the Protection of Virtual Asset Users enactedas of Jul 18, 2023 | [5]governmentAct on the Protection of Virtual Asset Users (press release)Financial Services Commission, Republic of Korea |
Overview
A blockchain is an append-only distributed ledger. Transactions are grouped into blocks, each referencing the previous block by hash, and validated by a consensus mechanism across independent nodes. Public blockchains such as Ethereum are open networks; private or permissioned chains restrict participation.
Verified providers
Sponsored listings are labeled. Verification is independent of payment.TwoLegend
TwoLegend is a South Korean software development company specializing in blockchain mainnet, AI and enterprise software development.
View providerReferences
Independent source ratio 80% (4/5) · self-published 1- Level A · governmentIR 8202, Blockchain Technology Overview — National Institute of Standards and Technology (NIST) · accessed Oct 7, 2026 · Evidence page
- Level A · governmentBlockchain Technology Overview: NIST Internal Report 8202 Now Available — National Institute of Standards and Technology (NIST) · accessed Nov 11, 2026 · Evidence page
- Level C · officialBitcoin: A Peer-to-Peer Electronic Cash System — Bitcoin Project (bitcoin.org) · accessed Nov 11, 2026 · Evidence page
- Level C · officialOfficial claimThe Merge — ethereum.org · accessed Nov 10, 2026 · Evidence page
- Level A · governmentAct on the Protection of Virtual Asset Users (press release) — Financial Services Commission, Republic of Korea · accessed Oct 17, 2026 · Evidence page