Overview of Ethereum Forks

Forks, as modifications to the blockchain code, are common in various blockchain projects.

Disputes within the crypto community over a specific issue or the need to improve the blockchain's code are the two main reasons for forks.

Forks can range from minor corrections to the source code or incremental software updates to radical changes to the blockchain protocol. Forks can also be planned and unplanned.

Hard forks

Hard forks are rightly considered as the most significant forks. They involve an irreversible separation of the blockchain, in which the new protocol becomes completely incompatible with the old one.

Hard forks are major alterations to blockchain algorithms that cause the network to switch to a new version of the blockchain or split into two networks. Hard forks are often used to create new cryptocurrencies and launch new crypto projects.

Ethereum and its hard forks

Ethereum holds the second-largest market capitalization, and it is a popular blockchain for issuing tokens, creating decentralized platforms, and minting NFTs.  Ethereum is a blockchain with a very active cryptocurrency community that implements systematic changes to improve the network.

Each new Ethereum hard fork is designed to solve certain user problems.

Ethereum's most famous hard forks

Since its launch on July 30, 2015, Ethereum has been updated multiple times. The most famous hard forks are:

• Frontier (July 30, 2015);
• Frontier Thawing (September 7.2015);
• Homestead (March 14, 2016);
• Ethereum Classic (July 20, 2016);
• Tangerine Whistle (October 18, 2016);
• Spurious Dragon (November 22, 2016);
• Byzantium (October 16, 2017);
• Constantinople (February 29, 2019);
• Istanbul (December 8, 2019);
• Muir Glacier (January 2, 2020);
• Beacon Chain (December 1, 2020);
• Berlin (April 15, 2021);
• London (September 5, 2021);
• Merge (Bellatrix and Paris) (September 15, 2022).

Frontier

Frontier is not actually a hard fork, but we need to start with it because it is an event related to the launch of the main Ethereum blockchain. Its main purpose is to allow developers to create dApps and new cryptocurrencies. Ethereum was originally conceived as a large-scale ecosystem, which it is at the moment.

Frontier Thawing (Ice Age)

This is an unscheduled hard fork implemented to improve the security and speed of blockchain updates.

Homestead

The main goal of this fork was to avoid centralization. Transactions in the network's cryptocurrency (ETH) became available to network users, and they could also use smart contracts.

After that, Ethereum became a full-fledged DeFi project. Its native coin became popular, and many crypto users invested in Ethereum, boosting ETH trading in the cryptocurrency community.

Ethereum Classic

Ethereum Classic became one of the first serious tests of the Ethereum project. This hard fork was conducted after the failed DAO.

DAO (decentralized autonomous organization) was an event during which the team raised $150 million by token sales, but an unknown hacker stole $50 million in ETH.

The whole thing forced the developers to implement a hard fork to recover the stolen money. As a result, the blockchain split into two chains: Ethereum Classic and the mainnet.

The coins stolen from the network were locked in an intermediate account for 28 days, as specified in the smart contract's code. During this time, a hard fork was conducted to roll back fraudulent transactions. Users who had their ETH (Ethereum) stolen had it returned to the main network. At the same time, those users who did not support the hard fork continued to work with the old blockchain, where ETH was stolen. This network and coin were renamed ETC (Ethereum Classic).

Tangerine Whistle

DAO and the mainnet split were still under discussion when another DDoS attack was launched against the network. The blockchain was flooded with empty transactions, causing problems for real ones and their inclusion in blocks.  

This triggered an unscheduled Tangerine Whistle fork. The goal is to increase the cost of executing some code to make an attack extremely expensive for criminals.

Spurious Dragon

Besides the flood of empty transactions, criminals tried to disable the network by creating empty accounts. Attackers created empty accounts and transferred zero balances. The accounts contained essentially no data, but the transactions were still recorded on the blockchain, increasing its size and delaying normal transactions.

These attacks were conducted from 8 million unused addresses and increased the time required to create a block by 1-2 seconds.

As a result, another hard fork was implemented to mitigate the attacks' consequences, adjust the costs of some transaction codes, and clear the network of empty balances.

Metropolis Update: Byzantium and Constantinople

A major Metropolis hard fork has been split into 2 parts: Byzantium and Constantinople.

Byzantium

Metropolis updates began with the Byzantium hard fork. This fork has been on the Ethereum roadmap since 2015. It resulted in:

• transaction confirmation rate increase;
• reduction of the miner's reward from 5 to 3 ETH;
• delay of the difficulty bomb for a year and a half.

Difficulty bomb is a software code, gradually increasing complexity of ETH mining offering PoW consensus algorithm and, as a result, an increase in the cost of block generation.

• transaction privacy increase.

Constantinople

This is the second phase of the Metropolis update. The miner reward was reduced even more (from 3 to 2 ETH) while the mining speed increased (about 14 seconds). This fork also set the stage for the Ethereum blockchain to switch to a hybrid PoW/PoS consensus mechanism.

As a result of the Constantinople fork, Ethereum became faster, more efficient, and more convenient. Smart contracts became easier to develop, and certain operations in the Ethereum code were simplified.

Istanbul

The update was aimed at solving such problems as:

• increasing resistance to DDoS attacks;
• changes in gas (commission) calculations;
• increasing the scalability of the blockchain;
• ensuring network compatibility with PoW-based coins.

Muir Glacier

The Istanbul fork was not entirely successful, with fewer than half the nodes having installed the required software by the time of the update. Blockchain mining time began to grow, and on January 2, 2020, Ethereum conducted Muir Glacier fork, the main purpose of which was to delay the difficulty bomb once again.

Beacon Chain: the beginning of Ethereum 2.0

This fork can be worthily called one of the most anticipated. The crypto community has been waiting for the launch of ETH 2.0 for several years. Many investors wanted to start using the Beacon Chain as soon as possible.

The Beacon Chain is an empty network without tokens, transactions or even dApps. It was created with the sole purpose of being a Proof-of-Stake consensus blockchain.

Since the Beacon Chain is an empty blockchain, it could merge with the Ethereum network and replace PoW consensus with PoS. Which, in fact, has already happened.

Developers created the first blockchain on December 1, 2020.  They were backed by not by miners, but by validators. Validators here are users who invested 32 ETH each and collected 524,288 ETH.

Berlin

This hard fork is essentially the second phase of Istanbul and preparation for the London fork.
Berlin suggested several improvements:

• reducing fees;
• different types of transactions;
• faster transaction processing;
• new types of trade transactions.

London

Another system update to the latest phase of Ethereum 2.0. London became quite a controversial subject. Some users liked it for lower commissions; others didn't like EIP-1559, which reduces transaction confirmation fees.  

EIP (Ethereum Improvement Proposal) is a separate proposal to improve Ethereum. Such proposals include hard forks.

Merge

On September 15, 2022, the anticipated Merge was completed on the Ethereum network. 
The second-most-capitalized cryptocurrency switched from a Proof-of-Work to a Proof-of-Stake consensus mechanism.  

The Merge was divided into 2 phases: Bellatrix and Paris. Merge officially launched with the Bellatrix fork on September 6, 2022. Bellatrix is a consensus-level blockchain update. Paris involved the execution layer. This update moved the Ethereum network from Proof-of-Work to Proof-of-Stake.
 

The day after the Merge happened, two hard forks of the network were launched: ETHW and ETHF. Their main difference is the support of the PoW consensus algorithm.

The Ethereum community has been on its way to Merge for six years. Many consider this hard fork not just a fork, but an important milestone in the cryptocurrency's history.

The Merge demonstrates that a decentralized, publicly available network can operate in the most energy-efficient manner possible.