# Fork

Source URL: https://help.blockstream.com/education/glossary/fork
Updated: 2026-05-26T17:21:56.000Z
Letter: F

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A fork in Bitcoin refers to a change in the protocol rules. There are two main types:

**Hard fork**:A change incompatible with previous versions, causing the blockchain to split into two if not all nodes upgrade. It results in an entirely new blockchain.

**Soft fork**: A backward-compatible change, meaning the new chain is still compatible with the old one. Older nodes see new transactions as valid (but may not understand them), ensuring a single continued chain. It tightens or adds rules without ostracizing previous nodes.

Two prominent soft forks in Bitcoin were Segregated Witness (SegWit) in 2017 and Taproot in 2021.

![](https://storage.googleapis.com/dxp-production-assets/content/glossary/FO82350175AC4_3.png)

Navigation: Blockstream Help Center > Education > Glossary > Fork

## Related Terms in This Letter
- [Federations](https://help.blockstream.com/education/glossary/federations)
- [Fedimint](https://help.blockstream.com/education/glossary/fedimint)
- [Fee Estimates](https://help.blockstream.com/education/glossary/fee-estimates)
- [Fork](https://help.blockstream.com/education/glossary/fork) (current)
- [FROST](https://help.blockstream.com/education/glossary/frost)
- [FUD](https://help.blockstream.com/education/glossary/fud)