Immutability
Immutability is the property of a blockchain where confirmed data cannot be altered without redoing the underlying consensus work, preserving historical integrity.
In proof-of-work systems, immutability emerges from the cumulative work required to reorganize blocks. Deep confirmations make changes impractical. Economic costs and decentralization further deter rewriting history.
"A transaction with 6+ confirmations on Bitcoin Cash is extremely costly to reverse due to required hash power and coordination."
"Nodes verify, store, and replicate blocks; altering history would require convincing the majority of honest nodes."
Immutability is practical, not absolute. Protocol upgrades and rare chain reorganizations are possible. Governance changes must balance safety with necessary improvements.
"A short reorg can occur during competing blocks; finality increases with depth."
"Hard forks change rules moving forward without modifying prior blocks, preserving historical records."
Related Terms
Blockchain
→A decentralized, peer-to-peer ledger system composed of a continuous chain of blocks.
Consensus
→The process used by blockchain networks to agree on the state of the distributed ledger.
Finality
→The point at which a transaction is considered irreversible and economically infeasible to revert.
Proof of Work (PoW)
→A consensus algorithm where computing power is used to solve complex problems, verify transactions, and create new blocks.
All terms and definitions may update as the Cryptionary improves.
