Immutability
blockchain · security
The practical resistance of confirmed blockchain history to alteration, created by consensus, replication, and economic cost.
- Also known as
- tamper-resistance, append-only ledger
Immutability means that once data is deeply confirmed, changing it becomes impractical rather than merely inconvenient. In proof-of-work systems, an attacker would need to redo enough work to replace history and convince nodes to accept the heavier valid chain.
Blockchain immutability is not absolute. Short reorganizations, consensus bugs, emergency interventions, or deliberate hard forks can affect what history a community recognizes.
Related terms
Blockchain
→A distributed ledger made of cryptographically linked blocks that record transactions under shared consensus rules.
concept · blockchain · technology
Consensus
→The process by which blockchain participants agree on valid transactions, blocks, and ledger history.
security · blockchain
Finality
→The rules or confidence used to judge whether a confirmed transaction can still be reversed.
consensus · blockchain
Proof of Work (PoW)
→A consensus mechanism that makes block production require verifiable computational work.
mining · blockchain · consensus