GlossaryAdvanced
Fork Choice Rule
The algorithm a node uses to decide which of multiple competing chain histories it should treat as the legitimate, canonical one.
A fork choice rule is the specific algorithm a node uses to decide, when faced with multiple competing valid chain histories, which one it should treat as the legitimate, canonical chain — for example, Bitcoin's classic rule generally favors the chain with the most accumulated proof-of-work.
Every blockchain network needs some fork choice rule to resolve temporary disagreements (see Kaavon's "Reorg" glossary definition) between nodes about which chain is correct, and the specific rule used is a core, defining part of a network's overall consensus mechanism design.
Examples
- Bitcoin's classic fork choice rule generally favors whichever valid chain has the most accumulated proof-of-work behind it.
- A network's fork choice rule is a core, defining component of its overall consensus mechanism, not a minor implementation detail.