Fork (soft fork, hard fork)
Also · Soft fork · Hard fork · Chain split
A fork is a divergence in Bitcoin’s rules, software or chain. A soft fork tightens the rules so old nodes still accept new blocks. A hard fork loosens them and splits off old nodes.
The word fork covers several things. A code fork is just a copy of a software project. A chain fork happens when 2 miners find a block at the same time, and resolves within a few blocks. The forks that matter for governance are changes to the consensus rules.
A soft fork makes the rules stricter. Blocks valid under the new rules remain valid for nodes that did not upgrade, which is how SegWit and Taproot were deployed. A hard fork makes previously invalid blocks valid. Nodes that keep the old rules reject them, so a lasting split is possible if both sides keep mining. Bitcoin Cash in 2017 is the best-known example.
In French · Fork (soft fork, hard fork)
