A hard fork is a protocol upgrade that permanently splits a blockchain into two incompatible chains when nodes do not agree on the new version.
Understanding Hard Forks in Blockchain
A hard fork is a radical change to a network’s protocol that makes previously invalid blocks and transactions valid, or vice-versa. This bifurcation results in two diverging chains — one that follows the new protocol and one that continues along the old path.
What Triggers a Hard Fork?
- Major upgrades or changes in protocol.
- Security fixes to address vulnerabilities.
- Reversing transactions, often in response to a network attack.
- Adding new functionalities or features.
- Resolving significant disputes within the community.
Hard Fork Outcomes
- The creation of a new cryptocurrency if consensus is not achieved.
- Potential disappearance of one chain if an upgrade garners unanimous support.
For instance, Ethereum’s response to the DAO hack led to two separate chains: Ethereum (ETH) and Ethereum Classic (ETC).
Hard Fork vs. Soft Fork
Unlike soft forks, which allow for backward compatibility, hard forks do not permit the new and old protocols to communicate, resulting in a permanent split.