Definition
A hard fork is a type of blockchain protocol change that introduces new rules incompatible with the previous version of the software. It creates a permanent divergence in the blockchain’s history if some nodes continue following the old rules while others adopt the new ones. After a hard fork, blocks validated under the new rules are not recognized as valid by nodes that remain on the old protocol.
In Simple Terms
A hard fork is a major rule change in a blockchain that is not backward compatible. When it happens, the network can split into two versions if some participants keep using the old rules and others switch to the new rules, leading to two separate chains that no longer fully agree.
Context and Usage
The term hard fork is commonly used in discussions about blockchain governance, protocol upgrades, and disagreements among network participants. It appears in technical documentation, community debates, and ecosystem roadmaps when describing significant changes to validation rules, data formats, or consensus parameters that may cause a chain split. It is often contrasted with less disruptive forms of protocol modification.