Fork Definition in Crypto

A fork is a change to a blockchain’s rules or code that can push the network onto a new path. Because public blockchains are open source and run by many independent nodes, rule changes can either update the existing chain or split it into two histories that share the past but move forward differently.

How a fork works

Nodes follow software that validates blocks according to a protocol. When developers and the community introduce new rules, nodes choose whether to adopt them. If the new rules remain compatible with the old ones, the network keeps a single chain. If they are not compatible, the network can diverge into two separate chains that keep the same transaction history up to the split, then record different blocks from that point on. 

Types of forks

Soft fork

A soft fork is a backward-compatible update. Upgraded nodes enforce new rules, while older nodes still see the new blocks as valid. Think of it as a regular software update that tightens the rules without breaking older versions. The end result is one chain. 

Hard fork

A hard fork is a non-compatible change. The new rules can no longer be validated by older nodes, so the network can split into two independent chains if not everyone upgrades. Each chain continues under its own rules. This is how entirely new cryptocurrencies have been created from existing ones.

Why Forks Happen

Forks usually appear for straightforward reasons: adding features, improving security, or resolving disagreements about a project’s direction. Sometimes teams also reuse code to launch a new network with different goals. All of these are normal outcomes in an open-source ecosystem.

What It Means for Users

During a soft fork, users typically continue as usual, since the network remains a single chain and older nodes can still interact with upgraded ones. During a hard fork, users may need to choose which chain to support by running software for that chain or by relying on service providers that have chosen a side. If both chains persist, two distinct assets can exist that share the same pre-fork history.

Notable Examples

Community splits over technical choices have produced well-known networks. For example, Bitcoin Cash came from the Bitcoin codebase through a hard fork that pursued a different approach to scaling. Ethereum Classic continued on the original Ethereum chain after a controversial period, while the main Ethereum chain moved ahead with different priorities. These examples show how social consensus decides which rules a network follows.