Hard Fork

A Hard Fork is a permanent split of a blockchain into two separate networks that will coexist simultaneously, running in parallel, but not affecting one another.

A hard fork, by virtue of the building blocks of all things blockchain, is really just a software update to an existing blockchain’s code.

Some of the nodes accept the software update, while some of the nodes don’t.

The nodes that do accept the update will create a whole new blockchain.

Any blocks verified and added to the original blockchain are not added to the new blockchain.

Hard forks happen for various reasons, including

fixing security issues,
unreconcilable disputes within the developer community,
reversing transactions involved in a hack,
adding new features,
changing the fee structure or mining rewards, and
overhauling existing code that can’t simply be patched.

Some Ethereum miners are considering a hard fork of the Ethereum blockchain due to the upcoming Merge taking place in September of 2022.

The Merge intends to switch the Ethereum consensus mechanism from Proof-of-Work (PoW) to Proof-of-Stake (PoS), eliminating the rewards that miners receive for validating transactions.

The PoW Etherem blockchain would be called ETHPoW post The Merge.

Bitcoin went through several hard forks since it’s birth, including

Bitcoin XT
Bitcoin Classic
Bitcoin Unlimited
Bitcoin Cash
Bitcoin Gold
Bitcoin SV
eCash
Litecoin

Several more forks took place.

Some hard forks, like Bitcoin Cash and Litecoin, have had success in staying popular and relevant. They are both still in the top 30 largest market cap cryptocurrencies.

Other hard forks have lost wider support, with diminishing network activity and trading volumes, usually resulting in the chains shutting down.

Related Terms

Soft Fork

In relation to blockchain technology, a soft fork involves introducing changes to a blockchain’s underlining protocol or software that are minor in nature. These software updates can take the form of new blockchain functionality, upgrades to network performance, enhancements that correct security issues, or even changes to the consensus rules that govern how blocks are created and validated on a blockchain. Forks are necessary for providing decentralized blockchains a way to make changes to the blockchain since there isn’t a central authority governing all aspects of blockchain development and evolution.

Fork

When developers make changes to a blockchain, such as adding new blockchain functionality, correcting security issues, creating entirely new coins, or even changing the consensus protocol that governs how blocks are created and validated on a blockchain.

The Merge

The Merge signifies a time in the future when the Ethereum blockchain transitions from the proof-of-work (PoW) consensus mechanism to a proof-of-stake (PoS) blockchain.

Ethereum (ETH)

Ethereum is a decentralized blockchain platform that makes digital money, global payments, and applications possible using open-source software and smart contract functionality. The big difference between the two is that Ethereum is programmable, meaning you can build and use decentralized apps on the network. That means the Ethereum blockchain can be programmed to do virtually anything.

Bitcoin (BTC)

Bitcoin (BTC) is most well known as a digital decentralized cryptocurrency, without a central bank or single administrator, that can be sent from user to user on the peer-to-peer Bitcoin network without the need for intermediaries, such as payment gateways or banks or routing services. Think of bitcoin as Internet money, that you can send and receive directly, to and from anyone, and you can use it to pay for stuff.