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In Brief
A fork is a change to a blockchain's protocol that causes the chain to diverge a soft fork is backward-compatible, while a hard fork creates a permanent split that can result in a new, separate cryptocurrency.
What Is a Fork?
A fork is a change to the rules (the protocol) of a blockchain. Because a blockchain is maintained by many independent nodes, a change in the rules can cause the chain to split or diverge. Forks are how blockchains upgrade, fix bugs, or resolve disagreements within their communities.
Forks fall into two main categories: soft forks, which are backward-compatible, and hard forks, which are not and can create an entirely new blockchain and coin.
Soft Fork vs Hard Fork
| Feature | Soft Fork | Hard Fork |
|---|---|---|
| Backward compatible | Yes | No |
| Old nodes still valid | Yes | No (must upgrade) |
| Creates a new coin | No | Sometimes |
| Rule change | Tightens rules | Changes/loosens rules |
| Example | SegWit (Bitcoin) | Bitcoin Cash split from Bitcoin |
How Does a Hard Fork Work?
Developers or the community propose a change that is not backward-compatible.
Nodes that adopt the new rules and nodes that keep the old rules can no longer agree.
The blockchain permanently splits into two separate chains at a specific block.
Each chain continues independently, often with its own coin and community.
Holders at the time of the split typically receive coins on both chains.
A famous example is Bitcoin Cash (BCH), which split from Bitcoin in 2017 over a disagreement about block size.
How Does a Soft Fork Work?
A soft fork tightens the rules so that new blocks are still recognized as valid by nodes running the older software. This means the upgrade can roll out gradually without splitting the chain, as long as a majority of participants adopt it. Bitcoin's SegWit upgrade is a well-known soft fork.
Why Do Forks Happen?
Protocol upgrades — adding new features or improving performance.
Bug and security fixes — correcting flaws in the protocol.
Community disagreements — differing visions for a project's direction.
Reversing attacks — in rare cases, to undo the effects of a major hack.
Forks and Trust Wallet
When a hard fork creates a new coin, holders may be entitled to the forked asset. Because Trust Wallet is non-custodial, you control the private keys that grant access to assets on both chains. Trust Wallet supports a wide range of forked and independent coins across 100+ blockchains, so you can store and manage them securely in one place.