Fork
16/04/2026
A fork in blockchain is a change to the protocol rules. When nodes disagree on the rules, the chain can split — the original and the new version diverge. Forks can be planned upgrades or contentious splits.
Hard fork
A hard fork is a non-backward-compatible rule change. Old nodes reject blocks produced by new nodes. If the community splits, two separate chains emerge — each with its own coin.
Examples:
- Bitcoin → Bitcoin Cash (2017) — disagreement over block size limit
- Ethereum → Ethereum Classic (2016) — disagreement over DAO hack rollback
- Bitcoin Cash → Bitcoin SV (2018) — further split over block size
Soft fork
A soft fork is a backward-compatible upgrade. New rules are stricter — old nodes still accept new blocks as valid, so no chain split occurs if most miners adopt the change.
Examples:
- SegWit (Bitcoin, 2017) — restructured transaction data without a block size change
- Taproot (Bitcoin, 2021) — improved scripting and privacy
Fork vs. new coin
A forked coin starts with the same transaction history as the original up to the fork block. After that, the chains diverge independently. Holders of the original coin at the fork block typically receive an equal amount of the new coin.
Relevance to miners
- Forks can change mining algorithms, block rewards, or DAA rules — directly affecting profitability
- Hard forks sometimes create a new mineable coin (free coins for holders)
- Algorithm changes may make existing hardware obsolete or newly profitable
