There are two broad categories. A soft fork tightens the rules in a backward-compatible way, so nodes that haven't upgraded their software can still recognise blocks produced under the new rules as valid. A hard fork changes the rules in a way that isn't backward-compatible, meaning upgraded and non-upgraded nodes can no longer agree on what counts as a valid chain. If the network doesn't unanimously adopt a hard fork's new rules, the blockchain can permanently split into two separate networks, each continuing with its own transaction history from the fork point onward and, often, its own distinct coin.
Forks happen for different reasons: routine protocol upgrades that add features or fix issues, or genuine disagreements within a community about the network's future direction. This is a normal part of how open blockchain protocols evolve, not inherently a sign of trouble. That said, holders of a coin at the time of a contentious hard fork can end up holding a balance on two separate chains afterward, and accessing or using coins on each resulting chain depends on whether wallets and exchanges choose to support it.
From a user's perspective, exchanges and wallet providers typically decide which resulting chain to list and support after a contentious hard fork, and that decision is often what determines how easily someone can actually access and use coins on each side of the split. Software upgrades carried out as soft forks, by contrast, generally roll out without creating a competing chain at all, since nodes that haven't yet upgraded can continue following along under the tightened rules rather than being pushed onto an incompatible version of the network.
Key takeaways
- A fork is a change to a blockchain's rules, ranging from a routine backward-compatible upgrade to a full split into two separate networks.
- A hard fork is not backward-compatible and can create two separate chains if the network doesn't unanimously adopt the new rules.
- Forks are a normal part of how open blockchain protocols evolve and don't automatically indicate a problem with a network.
Fork — frequently asked questions
What's the difference between a soft fork and a hard fork?
A soft fork tightens the rules in a way older software can still recognise as valid, while a hard fork changes the rules in a way that's incompatible with older software, which can split the network into two separate chains.
Do I lose my coins in a fork?
Typically not. In a contentious hard fork, holders generally end up with a matching balance on both resulting chains, though accessing and using each chain's coins depends on wallet and exchange support.
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