What is a Hard Fork?

A hard fork is a change to the protocol of a blockchain that is not backward-compatible, meaning that all participants in the network must upgrade to the latest version of the software or risk becoming irrelevant on the network. This results in a split in the blockchain, creating two separate and incompatible versions of the same blockchain.

Hard forks are typically used to implement new features or make major changes to the underlying architecture of the blockchain. For example, a hard fork may be used to increase the block size limit or to add new consensus algorithms.

Hard forks can occur for a variety of reasons, including the need to address security vulnerabilities, implement new features, or resolve governance disputes within the community. In some cases, a hard fork may be proposed by the core development team, while in others, it may be initiated by a community of users or stakeholders who feel that the existing blockchain is not meeting their needs.

The process of a hard fork typically involves a significant amount of coordination and communication between stakeholders, as well as the development and deployment of new software. This can be a complex and time-consuming process, and it is important to carefully consider the potential consequences of a hard fork before proceeding.

One of the most important considerations when it comes to hard forks is compatibility with existing systems and applications. If a hard fork results in a split in the blockchain, it can lead to confusion and uncertainty among users and may impact the overall security and stability of the network.

In conclusion, a hard fork is a major change to the protocol of a blockchain that results in a split in the network. It can be used to implement new features or resolve disputes, but it also carries the risk of community conflicts and compatibility issues. Careful consideration and communication are key to ensuring a successful hard fork.

Simplified example

A hard fork in blockchain is like changing the rules of a game. Imagine you and your friends are playing a game and someone suggests a new rule. If everyone agrees to the new rule, then you continue playing the game with the new rule. But if some people don't like the new rule, they might choose to stop playing with you and start playing with a different group that has different rules.

In blockchain, a hard fork is when some members of the network decide to change the rules of the system, but not everyone agrees to the change. When this happens, the network splits into two separate networks, each following their own set of rules. Just like how the group of friends split into two groups with different rules. One group continues to follow the old rules, while the other group follows the new rules.

History of the Term "Hard Fork"

The precise origin of the term "hard fork" is somewhat elusive, yet its emergence is linked to the realm of software development and version control systems during the early 2000s. This term denotes a distinct kind of software update characterized by changes that are incompatible with the previous version, resulting in a lack of backward compatibility between the updated and preceding software iterations.


Bitcoin Cash Hard Fork: In 2017, the Bitcoin network experienced a hard fork which resulted in the creation of Bitcoin Cash. The hard fork was a result of disagreements within the Bitcoin community over the best way to scale the network to handle increasing numbers of transactions. Those who supported the hard fork believed that the block size limit needed to be increased to allow for more transactions to be processed, while those who opposed the hard fork believed that other solutions, such as SegWit, were better.

Ethereum Classic Hard Fork: In 2016, the Ethereum network experienced a hard fork in response to the theft of over 50 million ETH from the DAO (Decentralized Autonomous Organization). The hard fork was designed to reverse the theft and return the stolen funds to their rightful owners. However, some members of the Ethereum community opposed the hard fork, as they believed that it violated the principles of immutability and censorship resistance that are central to the blockchain. These individuals continued to support the original, un-forked Ethereum network, which became known as Ethereum Classic.

Bitcoin Gold Hard Fork: In 2017, the Bitcoin network experienced another hard fork which resulted in the creation of Bitcoin Gold. The purpose of the hard fork was to change the mining algorithm used by the network, from SHA256 to Equihash, in order to make it more resistant to ASIC mining. This was intended to make the mining process more decentralized, as ASICs are typically manufactured by a small number of companies, whereas the Equihash algorithm can be mined on a wider range of hardware.

  • Fork (Blockchain): A divergence in the blockchain which occurs when different versions of the protocol software are used to create new blocks by miners.

  • Byzantium Fork: A term used in the blockchain and cryptocurrency space to refer to a specific type of software upgrade.