Knowledge base
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What is a Hard Fork and a Soft Fork in Cryptocurrencies?

The world of cryptocurrencies is a complex one, filled with opaque terminologies that define its landscape. Among these terms are "hard fork" and "soft fork," which play a pivotal role in the evolution of cryptocurrencies.


This article will dissect these two concepts, shedding light on their meanings, characteristics, significance, and real-world examples.

What is a Fork in Cryptocurrencies?

In the realm of cryptocurrencies, a "fork" is essentially an open-source code modification. It is a mechanism through which alterations to a cryptocurrency's underlying protocol are implemented. Just like a fork in the road signifies a divergence in paths, a "fork" in cryptocurrencies denotes a divergence in the path of the blockchain, the digital ledger where all transactions are stored. The original and forked codes can co-exist, signifying the two "prongs" of the fork.

Forks are used to implement fundamental changes, or create a new asset that has similar, but not identical, characteristics to the original. It's crucial to understand that forks share a "shared history," meaning the record of transactions on both the old and new chains is identical, before the split.

Why are Forks Important in Cryptocurrencies?

Forks play a critical role in the evolution and growth of blockchain technologies. They act as catalysts for change, allowing the implementation of new features, enhancements, and adjustments to the cryptocurrency's protocol. Forks are often the outcome of disagreements over embedded characteristics within the crypto community, which can lead to substantial changes in the course of the cryptocurrency.

Forks also have the potential to spawn new cryptocurrencies. By creating a divergence in the blockchain, it’s possible that a fork creates a new cryptocurrency, with a ledger that differs after the fork, but shares a common history of the original blockchain before the fork.

Diving Deeper into Hard Forks

Definition and Characteristics of a Hard Fork

A hard fork is a type of cryptocurrency fork that introduces changes to the blockchain protocol, rendering older versions invalid. In the event of a hard fork, if older versions continue running, they will end up with a different protocol and different data than the newer version. This discrepancy can result in significant confusion and user issues.

Reasons for Implementing a Hard Fork

The reasons behind implementing a hard fork are varied. They may involve changing defining parameters related to the block size, the mining algorithm, or limits to additional information that can be added. A change to any of these rules could cause blocks to be accepted by the new protocol but rejected by older versions (or vice versa), potentially leading to serious problems.

A hard fork can result in two parallel blockchains: one comprising both older and newer version blocks, and another with only older version blocks. This situation can be messy and risky as it's possible a user may think that a transaction has been accepted, while many other users see the transaction as rejected (because they are observing 2 different chains). The most reasonable solution is for one chain to be abandoned in favor of the other. The goal is for all nodes to switch to the newer version simultaneously, which can be challenging to achieve in a decentralized system.

Real-World Examples of Hard Forks

A notable example of a hard fork is the creation of Bitcoin Cash from Bitcoin. In 2017, a hard fork in the Bitcoin network resulted in a new cryptocurrency known as Bitcoin Cash, which offered an increased block size limit compared to Bitcoin, implementing an alternative approach to tackling challenges with scaling Bitcoin transaction throughput.

Diving Deeper into Soft Forks

Definition and Characteristics of a Soft Fork

Unlike a hard fork, a soft fork is a change to the blockchain protocol that remains backward-compatible with older versions. That means that even after the soft fork, the old nodes in the network will still remain in consensus with nodes supporting the soft fork.

Reasons for Implementing a Soft Fork

Soft forks are generally implemented to tighten rules, make technical changes, or add a function that doesn't affect the blockchain's structure in any significant way. In the case of a soft fork, new version blocks will be accepted by old version nodes. However, the newer, "tighter" version may reject blocks older nodes consider valid. This backward compatibility is what sets soft forks apart from hard forks. It’s critical that a majority of the network supports the soft fork.

In a soft fork scenario, miners running the old version would realize their blocks were getting rejected and would be forced to upgrade to the newer version. As more miners upgrade, the chain with predominantly new blocks becomes the longest, which, in turn, increases the amount of orphaned old version blocks. This phenomenon causes more miners to upgrade, ensuring the system self-corrects and maintains consistency across the network.

Real-World Examples of Soft Forks

One example of a soft fork in the Bitcoin network is the implementation of the Segregated Witness (SegWit) update. SegWit was introduced to solve the issue of transaction malleability and improve Bitcoin's scalability. It was implemented as a soft fork, meaning that nodes running older versions of the Bitcoin software could still recognize and validate transactions after the update.


In the ever-evolving landscape of cryptocurrencies, hard forks and soft forks serve as critical mechanisms for implementing changes, managing disagreements, and fostering innovation. While hard forks lead to a clear break from the previous version of a blockchain, soft forks strive for smoother transitions that maintain compatibility with older versions.

Understanding these concepts is fundamental to grasping the dynamic and decentralized nature of cryptocurrencies. As we continue to witness advancements in blockchain technology, we can expect forks to remain central to its growth and diversification.