Soft Fork
A backward-compatible rule tightening where upgraded nodes enforce stricter limits and old nodes still follow along.
A soft fork narrows the rules rather than expanding them. Blocks valid under the new, stricter logic are still valid to old software, so nodes that don't upgrade keep working without splitting off.
Because it avoids a chain split, a soft fork is the gentler way to ship changes. Bitcoin's SegWit and later Taproot upgrades both arrived this way, adding features while keeping the network unified.
Related terms
A split in a blockchain's history or rules, whether a brief accident or a deliberate protocol change.
Hard ForkA backward-incompatible rule change that forces every node to upgrade, sometimes splitting one chain into two.
BlockchainA shared digital ledger that records transactions in linked batches, copied across many computers and hard to alter.
Consensus MechanismThe rules a decentralized network follows to agree on one valid history without trusting any central party.