What is a Blockchain Fork?
A blockchain fork occurs when developers update or modify the underlying software programming governing a decentralized network. Because public blockchains rely on independent nodes to maintain agreement on transaction history, changes to the protocol require adoption by network participants.
Types of Forks
When a protocol change is published, it generally results in one of two events:
- Hard Fork: A radical, backward-incompatible software change. Nodes running the original software cannot process transactions on the updated chain. Participants must choose whether to upgrade to the new version or remain on the unmaintained legacy chain. If a faction of the community chooses to maintain the old chain, the network splits into two separate blockchains with distinct cryptocurrencies (e.g., Ethereum and Ethereum Classic, or Bitcoin and Bitcoin Cash).
- Soft Fork: A backward-compatible software update where old and new nodes can continue to co-exist and validate transactions under the updated rules without splitting the network.
Primary Causes for a Hard Fork
- Routine Upgrades & Maintenance: Enhancing protocol performance or adding network capabilities, such as Cardano's update toward decentralized governance or Ethereum's upgrade enabling staked ETH withdrawals.
- Bug Fixes & Security: Correcting software vulnerabilities, errors, or network execution problems.
- Community Disagreements: Resolving philosophical or technical splits within a community regarding the future direction of a project.
- Emergency Interventions: Reversing major network exploits, such as the historic Ethereum DAO hack rollback.