Topic · How blockchains work
What is a soft fork?
- Quick fact 1
BIP 9 describes a way to coordinate soft fork activation using version bits.
Source: BIP 9: Version bits with timeout and delay (soft fork deployment)
- Quick fact 2
SegWit (BIP 141) was deployed as a soft fork.
- Quick fact 3
A hard fork, by contrast, loosens or changes rules so old nodes reject new blocks.
Source: bitcoin.org glossary: Hard fork
The short lesson
Blockchains change their rules through upgrades called forks. A soft fork is the gentle kind.
In a soft fork, the new rules are stricter than the old ones. Every block valid under the new rules is still valid under the old ones. So nodes that do not upgrade keep following the same chain. They just do not enforce the new rules themselves.
A hard fork is the opposite. It allows something old nodes reject, so everyone has to upgrade or end up on a different chain.
Real examples
What it means for you
Usually nothing to do. Your coins stay where they are. Be wary of anyone who says an upgrade means you must “migrate,” “validate” or enter your seed phrase on a website. That is a scam pattern, not an upgrade.
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Related terms
Go deeper in Lesson 4: The shared list everyone can check
More in How blockchains work
Common questions
Do I get new coins in a soft fork?
No. Soft forks do not split the chain into two coins.
Do I need to update my wallet?
Not to keep your coins. Updating may let you use new features.
Who decides a soft fork?
Developers propose it, and node operators and miners coordinate activation.
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Reviewed and sources
Written and reviewed by Joshua Baskin, founder. Last reviewed . How we check facts · Report an error
Education only. Not investment, tax or legal advice. We do not pick coins.