In blockchain networks, a fork refers to a situation where changes to the underlying protocol rules cause the blockchain to split into different paths. These changes are typically proposed by developers or the community to improve network functionality, fix vulnerabilities, or adjust consensus mechanisms. There are two main types: hard forks and soft forks.
Hard Fork
A hard fork is a non-backward-compatible upgrade that requires all nodes to update to the new version. Nodes that don't upgrade will remain on the old chain, which may continue operating or eventually become obsolete.
Hard forks are typically used to implement major functional changes (such as scaling solutions or new consensus mechanisms) or to resolve community disagreements (as seen when Bitcoin split to create BCH).
Soft Fork
A soft fork is a backward-compatible upgrade where non-upgraded nodes can still validate new blocks but cannot participate in new features. Nodes running old versions will follow the chain recognized by the majority of computing power, preventing a network split.
Soft forks are commonly used to optimize rules (like adjusting block size limits) or fix security vulnerabilities without requiring mandatory updates for all nodes.
| Hard Fork | Soft Fork | |
| Compatibility | Not backward-compatible | Backward-compatible |
| Chain Split Risk | May create two chains | Single chain continues |
| Upgrade Difficulty | Requires a broad consensus | Needs majority miners’ support |
| Use Cases | Major protocol changes, chain splits | Optimizations, security fixes |