Fork (Blockchain)

Forks happen when two blockchains are created from a single one. This happens when there is a disagreement about the rules of the blockchain, or when someone wants to create a new blockchain with different rules. Usually, the original blockchain continues to run while the new one is created.

Fork Definition

If you are new in the crypto space, you have probably been seeing the term “hard fork” being thrown around ever so often. So what is a cryptocurrency fork?

Assuming you already know a bit about blockchain technology, a hard fork is, to put it simply, a change in the rules used to validate transactions.

A bitcoin fork is when a change in the rules used to validate transactions occurs, the blockchain network splits into two, one which uses the old rules and one which uses the new rules. A good example is Bitcoin (BTC) and Bitcoin Cash (BCH).

When a hard fork occurs, a blockchain network splits into two, one which uses the old rules and the new one which uses the new rules. Think of it as a software upgrade. At the point it occurs, there is a permanent divergence and old nodes will no longer be accepted in the upgraded one.

These technical events are decided through consensus. As expected, not everyone agrees to these upgrades and fallouts often occur. The result is a new chain of transactions and of course a new cryptocurrency such as bitcoin cash which is forked from bitcoin.

As Coinbase’s David Farmer put is in his blog “A “fork” is a change to the software of the digital currency that creates two separate versions of the blockchain with a shared history.”

Why hard fork?

Hard forks occur for various reasons. Often, it is done to add new functionalities or to plug some vulnerabilities in the network.

It could also be done to reverse transactions such as when there has been a 51% attack. This is where rogue miners take control of the majority of the network and add fraudulent transactions. A hard fork is usually necessary to roll back such transactions. One such attack occurred on the Verge network.

Developers may, for example, want to change the rules to increase block sizes, say from 1MB per block to 8MB per block for faster transactions as in the case of Bitcoin Cash. This will require a hard fork.

Once done, the new version will no longer accept transactions confirmed by nodes that have not been upgraded. This can be contrasted to a soft fork where changes are backward compatible. This means there is some kind of interoperability between the old and new protocols. One example of a soft fork is Segwit.

Which fork survives?

Whether the old protocol survives depends on how many people are willing to commit their computing power and how many developers are still willing to support it. It’s all up to the market to decide.

The earlier ethereum protocol for example still exists alongside ethereum classic. The dominance of one over the other solely depends on its adoption. Often, one chain becomes favoured over the other but both often manage to exist.

When a split happens, holders of the original cryptocurrency, say bitcoin also get the new cryptocurrency like bitcoin cash. This really depends on whether you actually hold the keys to your tokens. People often look for the next bitcoin fork dates for an opportunity to earn free coins. You should, however, exercise due diligence before claiming the new coins.

A snapshot of the block number or block height where the fork occurred is taken. The bitcoin hard fork date that created bitcoin cash was August 1.

Hard forks 2018

A lot of btc forks actually occurred in 2017 other than bitcoin cash or bitcoin gold. In terms of bitcoin hard fork 2018, perhaps the more notable one is bitcoin private in January which is a privacy-focused coin. There aren’t many promising btc upcoming forks in 2018.

Certain exchanges, for example, did not support the new protocol and users, in this case, do not get awarded.

Exchanges like Coinbase, for example, consider factors such as demand and the value of the new cryptocurrency before deciding to support it.


To wrap up, a hard fork is a change of rules in a blockchain protocol that validates or invalidates transactions. It is done for security reasons, to add new functionalities to the network or to roll back transactions.

Honestly speaking, some bitcoin forks are solely done to generate some quick money for the developers and many others are outright scams. Stay alert.