Fork Choice Rule

The fork choice rule is the logic used by blockchain nodes to determine which chain is the valid one when multiple versions of the ledger exist. In the event of a network partition or a deliberate fork, nodes must have a consistent way to choose the path forward.

This rule is a fundamental component of the protocol, ensuring that all participants eventually converge on a single, shared history. In Bitcoin, the rule is to follow the chain with the most cumulative proof-of-work.

Other protocols may use different criteria, such as the highest number of validators or a specific weight assigned to blocks. The fork choice rule is what gives the network its resilience and ability to self-heal after disruptions.

It is the primary mechanism for maintaining consensus and preventing the permanent splitting of the network into multiple competing versions.