# Immutable

> Cannot be changed once recorded. The standard property of confirmed blockchain history.

Canonical URL: https://fudfomo.co/glossary/immutable
Source: What The Block! Dictionary v1.0 (last updated 2026-04-25), browsable at https://wtb.fudfomo.co.

## Definition

Immutable means cannot be altered. Once a transaction is included in a confirmed block on a healthy blockchain, the cost of rewriting it grows quickly with each new block on top.

In practice, this is what makes a blockchain useful for ownership records: nobody can quietly edit the past. Off-chain data linked from the chain, like NFT images stored elsewhere, may not share the same property.

## Related terms

- [Blockchain](https://fudfomo.co/glossary/blockchain): A shared digital record of transactions that no single person or company controls. Everyone can read it, and changes are extremely hard to fake.
- [Finality](https://fudfomo.co/glossary/finality): The point at which a transaction is considered settled and unlikely to be reversed.
- [Confirmation](https://fudfomo.co/glossary/confirmation): A measure of how many blocks have been added on top of a transaction's block. More confirmations mean stronger settlement.
- [Smart Contract](https://fudfomo.co/glossary/smart-contract): A program that runs on a blockchain and does what it says, automatically.

## See the full catalogue

What The Block! covers more than 2,000 plain-English crypto terms, delivered as embeddable hover-state tooltips for crypto exchanges. https://wtb.fudfomo.co