Hard Fork


A hard fork is a significant change to a blockchain network’s protocol, resulting in a permanent divergence from the existing blockchain. It creates a new, non-backward-compatible version of the blockchain that requires all network participants to update their software. The original and the new chain operate independently, sometimes resulting in the creation of a new variant of the existing cryptocurrency.


The phonetic pronunciation of the keyword “Hard Fork” is:H – AY – R – D (rhymes with “card”)F – AW – R – K (rhymes with “cork”)In the International Phonetic Alphabet (IPA), it would be written as /hɑːrd fɔːrk/.

Key Takeaways

  1. A hard fork is a major change in a blockchain protocol that makes previously invalid blocks and transactions valid, or vice-versa.
  2. It requires consensus from all nodes on the blockchain network to upgrade to the new protocol, as it results in a permanent divergence from the previous version.
  3. Hard forks can be utilized to fix security risks, add new features, or to reverse transactions, but are generally considered to be a controversial measure due to potential community division.


The technology term “Hard Fork” is important primarily because it represents a significant change or update in a blockchain protocol that results in the creation of a new, separate blockchain network, often with its own currency and set of rules.

A hard fork occurs when a consensus cannot be reached among the participants in the existing blockchain network, and the proposed changes are not backward compatible with the previous version.

This has the potential to cause splits within the community, create unintended consequences, and challenge the stability and security of the associated cryptocurrencies.

However, hard forks also facilitate innovation and advancements within the blockchain technology ecosystem, signifying their importance in the continuous evolution of the digital asset landscape.


A hard fork, in the realm of blockchain technology, serves the purpose of implementing fundamental changes or upgrades to an existing blockchain protocol. Hard forks are often necessary when there is a need to introduce new features, address security loopholes, or modify key elements governing a particular blockchain system. These critical updates are intended to improve the overall functionality and efficiency of a blockchain network, making it more secure and adaptable to evolving technological demands.

By introducing alterations in the original set of consensus rules, a hard fork enhances the network’s capabilities while ensuring its long-term viability. Hard forks drive the blockchain community to remain unified, as they demand broad consensus and collaboration among the network’s participants to be successful. All users must agree to adopt the updated protocol and transfer to the new, diverged chain – effectively abandoning the old chain.

This process often leads to the emergence of two distinct blockchains, thereby creating a new cryptocurrency that is associated with the new chain. A well-known example of this is the creation of Bitcoin Cash following a hard fork from the original Bitcoin blockchain in 2017. In short, hard forks serve as essential milestones for implementing indispensable changes and maintaining the functioning and relevance of blockchain networks.

Examples of Hard Fork

A hard fork is a significant change to a blockchain network’s protocol that makes previously invalid blocks and transactions valid, or vice versa. This change in protocol often leads to the creation of a new, separate blockchain. Here are three real-world examples of hard forks in the cryptocurrency and blockchain industry:

Bitcoin Cash (BCH) – In August 2017, the Bitcoin network underwent a hard fork, resulting in the creation of a new cryptocurrency called Bitcoin Cash. This hard fork was implemented due to a disagreement within the Bitcoin community regarding the best way to scale the network and handle increasing transaction volumes. Bitcoin Cash increased the block size limit to 8 MB, allowing more transactions to be processed on its network, compared to the original Bitcoin (BTC), which maintained a block size limit of 1 MB.

Ethereum Classic (ETC) – In July 2016, the Ethereum blockchain experienced a hard fork in response to a major security breach known as the DAO (Decentralized Autonomous Organization) hack. The Ethereum community was split over whether to reverse the transactions and recover the stolen funds, resulting in the creation of Ethereum Classic, a new blockchain that maintained the original state of the Ethereum blockchain without the controversial changes. The main Ethereum chain implemented the fork and became the dominant chain with the majority of users, developers, and mining power.

Monero (XMR) – In April 2018, the Monero network underwent a hard fork to combat ASIC (Application-Specific Integrated Circuit) mining, which prioritizes decentralization and promotes more egalitarian mining distribution. The hard fork resulted in the creation of four new Monero projects: Monero Classic (XMC), Monero-Classic (XMC), Monero Original (XMO), and Monero 0 (XMZ). However, the original Monero (XMR) remains the dominant and most widely used chain, with frequent updates to maintain ASIC-resistance and promote decentralization.

Hard Fork FAQ

What is a Hard Fork?

A hard fork is a major change to a blockchain’s protocol, making previously invalid transactions or blocks valid, or vice versa. This requires all nodes or users to upgrade to the latest version of the protocol software, leading to a permanent divergence from the original blockchain.

Why do Hard Forks occur?

Hard forks occur when there are significant disagreements among the community regarding the direction or features of a blockchain project. They can be initiated to introduce new features, reverse transactions, or address security vulnerabilities. Essentially, a hard fork is a way to update or alter the blockchain protocol in a way that is incompatible with previous versions.

What are some famous examples of Hard Forks?

Some famous examples of hard forks include the Ethereum “DAO” hard fork in 2016, which resulted in the creation of Ethereum Classic, and the Bitcoin / Bitcoin Cash fork in 2017, which led to the coexistence of Bitcoin and Bitcoin Cash as separate cryptocurrencies.

What is the difference between a Hard Fork and a Soft Fork?

A hard fork is a radical change to the protocol that requires all nodes or users to upgrade their software, while a soft fork is a backward-compatible change that doesn’t require all nodes to update their software. Soft forks involve the tightening of rules or validation criteria, whereas hard forks involve the modification or expansion of rules and validation criteria, making them incompatible with previous blockchain versions.

How does a Hard Fork affect users and their cryptocurrencies?

When a hard fork occurs, users have to update their software to the latest version in order to continue participating in the network. Users who hold any cryptocurrency on the original blockchain may receive an equal amount of the new cryptocurrency created through the hard fork, depending on the specific circumstances and conditions laid out by the developers. However, it is essential for users to be cautious and research well before updating their software, as hard forks can be contentious and potentially result in the loss of funds if not handled correctly.

Related Technology Terms

  • Blockchain
  • Software Update
  • Consensus Algorithm
  • Decentralized Network
  • Cryptocurrency

Sources for More Information


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