Blockchain is often perceived as something static: data is recorded in a chain and should not be changed. Yet behind this apparent immutability lies a constantly evolving technology. Networks are updated, developers fix bugs, close vulnerabilities, improve transaction processing speeds and add new features.
And this creates a paradox: to keep a blockchain stable, it has to be changed regularly.
One of the ways these changes are introduced is through forks. Sometimes an update goes smoothly: participants install a new version of the software, the network keeps operating, and users barely notice anything. But sometimes participants cannot agree on the new rules. In that case, one path can turn into two.
This is where hard forks and soft forks come in — two different approaches to changing the rules of a blockchain. In one case, the new version of the protocol is incompatible with the old one; in the other, the network remains compatible with previous rules.
But these two technical terms involve much more than just a software update. Forks can change the structure of a network, affect cryptocurrency holders and even lead to the creation of entirely new projects.
What is a fork and why is it needed?
Every blockchain has a set of rules. They determine which transactions the network accepts, what a block should look like, who confirms transactions and which actions are considered violations of the protocol.
Over time, these rules may no longer meet the needs of the network. A blockchain may face a technical problem that needs to be fixed, the number of users may grow beyond the network's existing capabilities, or developers may want to integrate new technology into the protocol. Sometimes disagreements also emerge within the community over the future direction of the project.
In a centralized system, a decision by the platform owner or development team may be enough. Blockchain is different: the network is distributed among many independent participants. Developers can write new code, but they cannot force every node to install it. Miners, validators, node operators and other participants decide for themselves whether to accept the proposed changes.
A fork, therefore, is not just a matter of code. It is also a matter of consensus.
How does a blockchain reach a "fork in the road"?
It usually starts with a proposal to change the protocol. Developers identify a problem or a new requirement, prepare an update and describe how the rules will change. The reasons can range from fixing a vulnerability to making major changes to how the network operates.
Then comes the most important part — participants decide whether they are ready to accept the new version. If most of the network moves to the updated software, the blockchain continues along a single chain. To users, it may look like an ordinary update, even if the technical changes are significant.
But if some participants say "no" and remain on the old rules, a split can emerge. What happens next depends on the nature of the changes. If the old and new rules can coexist, it is a soft fork. If they are fundamentally incompatible, it is a hard fork.
Hard fork: when the old rules no longer work
A hard fork is the most radical type of update. During a hard fork, the new blockchain rules are incompatible with the old ones. A node that continues to run the previous version of the software may stop recognizing new blocks and transactions as valid.
Imagine that a blockchain previously prohibited a certain type of transaction. After a hard fork, developers decide to allow it. For the new software, everything is fine: the transaction complies with the new rules. An old node, however, continues to follow the previous requirements and considers the transaction invalid.
As a result, two groups of participants can be looking at the same network while following different rules. If old nodes simply shut down or gradually move to the new version, the process ends as an ordinary update. But if a significant number of participants decide to preserve the old protocol, a genuine split can occur — and two chains can begin developing independently.
A hard fork does not always mean a new cryptocurrency
There is an important misconception to clear up: not every hard fork creates a new cryptocurrency. Changing the protocol alone is not enough. The old and new versions of the blockchain must continue to exist and receive support from participants for a separate cryptocurrency to emerge.
If almost the entire network moves to the new version, the old chain may be left without users, infrastructure or economic activity. In that case, a new cryptocurrency effectively does not emerge.
But the history of the crypto market includes cases where participants failed to reach an agreement. In 2016, following the dispute over the aftermath of the DAO hack, the Ethereum community split. Most participants supported changing the blockchain's history, while others decided to preserve the original chain. Ethereum and Ethereum Classic emerged as a result.
In 2017, a similar scenario unfolded around Bitcoin. A dispute over network scaling and block size led to a hard fork and the creation of Bitcoin Cash. In 2018, disagreements within Bitcoin Cash resulted in another split, leading to Bitcoin SV.
These examples show that a hard fork can be much more than a technical update. Behind a dispute over code, there are often different visions for the future of a project. Some prioritize scalability, others security, while others want to preserve the project's original concept.
A technical disagreement can ultimately turn into an economic and political conflict within an entire ecosystem.
Soft fork: when the rules change but the network stays together
A soft fork takes a more cautious approach. With a soft fork, the new rules remain compatible with the old ones. This is usually achieved by making existing rules more restrictive rather than completely changing them.
Imagine that the old protocol allows ten types of a particular operation. After the update, the network allows only five. For new nodes, this becomes a mandatory restriction. Old nodes, however, can still accept those five types because they were already part of the permitted set.
As a result, different versions of the software can continue operating on the same network. This is the main advantage of a soft fork: it does not require every node to be updated at the same time.
Why can old nodes continue to operate?
After a soft fork, an outdated node may not be aware of all the new restrictions and features, but it can continue validating blocks according to the old rules. This makes it possible to introduce changes gradually without moving the entire network to a new version at once.
This approach is particularly important for decentralized blockchains. A network can contain thousands of independent nodes located in different countries and operated by different people and organizations. Coordinating a simultaneous update across all participants is practically impossible.
A soft fork allows the network to move forward without requiring a complete "restart".
Can a soft fork split the network?
In theory, yes. If part of the community strongly disagrees with the changes, those participants may try to continue operating under the old rules.
However, the design of a soft fork is intended to prevent this outcome. Because of backward compatibility, old and new nodes can continue to operate on the same chain. For this reason, a soft fork is generally considered a smoother way to update a blockchain.
SegWit and Taproot: how soft forks change Bitcoin
A good example is the SegWit upgrade activated on Bitcoin in 2017. It changed how some transaction data was processed and stored, allowing block space to be used more efficiently. SegWit also became an important technical foundation for the further development of second-layer solutions.
Another major example is Taproot, activated in 2021. The upgrade expanded the possibilities for working with complex transactions and smart contracts while making certain operations more compact and efficient.
Neither SegWit nor Taproot resulted in a new version of Bitcoin with a separate coin. The network continued to exist as a single blockchain.
This clearly demonstrates the difference between the two approaches: a soft fork allows the rules to change without necessarily breaking the connection with the previous version of the network.
What happens to cryptocurrency after a fork?
For a cryptocurrency holder, a fork is not simply news from the developer community. In the event of a serious network split, it can directly affect a user's assets.
If an update involves the entire network moving to a new set of rules, the holder's position usually does not change significantly. The assets continue to exist on the updated blockchain.
But if a hard fork results in two chains, the situation becomes more complicated. Both networks may preserve the transaction history that existed before the split. As a result, a user who held a certain amount of cryptocurrency before the fork may, under certain conditions, have a corresponding balance on both chains.
However, it would be incorrect to describe this as an automatic "doubling of money". The new cryptocurrency may be worth significantly less than the original, have limited liquidity or fail to receive sufficient market support. Different wallets and exchanges may also handle assets after a split differently.
That is why users should first determine which network their wallet supports and what steps are required to manage their assets safely.
Another issue is fraud. High-profile forks can become an opportunity for phishing attacks, with users being offered ways to "claim new coins", "activate a balance" or "confirm ownership".
No such process should require a seed phrase or private key. These credentials provide access to funds and should never be shared with third parties.
Why are forks important for the crypto industry?
A fork is one of the mechanisms that allows a blockchain to evolve without abandoning its existing infrastructure. At the same time, it can serve as a test for the community.
As long as participants agree on the project's direction, an update can proceed relatively smoothly. When interests diverge, a technical issue can quickly turn into a debate about the future of the entire network.
That is why crypto history is full of examples where changing a few protocol parameters resulted in the emergence of new projects and separate markets.
Hard forks and soft forks serve different purposes. A hard fork introduces incompatible changes. If some participants reject the new rules, the blockchain can split into two independent chains.
A soft fork preserves backward compatibility and allows new restrictions to be introduced without requiring every node to move to the latest version.
Put simply, a hard fork is a situation in which a blockchain may have to choose between two sets of rules. A soft fork makes it possible to change the rules without breaking the connection with the previous version of the network.
And that is why behind the seemingly technical terms "hard fork" and "soft fork" lie very real consequences — from a routine software update to the emergence of a new cryptocurrency and a complete shift in the balance of power within a blockchain ecosystem.
