Ethereum has undergone a transformative journey since its inception, evolving through multiple critical upgrades—known as hard forks—that have shaped its infrastructure, security, and scalability. These upgrades are essential milestones in Ethereum’s roadmap toward becoming a fully functional, energy-efficient, and scalable blockchain platform. This article explores the complete history of Ethereum hard forks, from its foundation to the pivotal Shapella upgrade, and how each phase contributed to the network's current state as a leading Proof of Stake (PoS) blockchain.
The Foundation of Ethereum
In June 2014, a group of visionary developers established the Ethereum Foundation in Switzerland with the goal of launching a decentralized computing platform. To fund development, they conducted a 42-day public crowdsale, issuing 60 million Ether (ETH). Early investors received up to 2,000 ETH per Bitcoin, later reduced to 1,399 ETH per BTC. This campaign raised approximately $18 million in Bitcoin, laying the financial groundwork for what would become the world’s second-largest cryptocurrency.
This initial distribution set the stage for Ethereum’s open and community-driven evolution—governed not by a central authority but by consensus and technical innovation.
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Understanding Blockchain Forks
A fork refers to a change in a blockchain’s protocol. It can introduce new features, fix vulnerabilities, or alter core mechanisms like consensus. Forks are categorized into two types:
Hard Forks vs. Soft Forks
- Hard forks create permanent divergences in the blockchain. Nodes must upgrade to the latest version; otherwise, they operate on an incompatible chain.
- Soft forks maintain backward compatibility. Older nodes can still validate transactions, though they may not recognize new rules.
Hard forks often result in new token distributions or even separate blockchains—such as Ethereum Classic—when part of the community refuses to adopt the change.
Ethereum Improvement Proposals (EIPs)
Upgrades on Ethereum are proposed and documented through Ethereum Improvement Proposals (EIPs)—standardized design documents outlining new features or optimizations. Created primarily by developers, EIPs undergo rigorous review before implementation. A single hard fork may incorporate multiple EIPs to achieve broader network improvements.
For example, EIP-1 defines the structure and guidelines for submitting EIPs, ensuring consistency across proposals.
Frontier: The Genesis of Ethereum
On July 30, 2015, Ethereum launched its first hard fork: Frontier. This marked the network’s official debut, featuring the genesis block containing over 8,893 transactions from early contributors. A total of 72 million ETH were pre-mined, with 12 million allocated to support ongoing development.
Frontier introduced the Ethereum Virtual Machine (EVM), enabling developers to run smart contracts—a revolutionary step in blockchain functionality.
Homestead: The First Planned Upgrade
The Homestead upgrade on May 14, 2016, was Ethereum’s first scheduled hard fork. It enhanced smart contract capabilities through updated Solidity compiler rules and removed centralized elements like “canary contracts,” reinforcing Ethereum’s decentralized ethos.
This upgrade signaled Ethereum’s transition from experimental phase to stable, production-ready platform.
The DAO Hack and Ethereum Classic Split
In 2016, The DAO—a decentralized autonomous organization—raised over $150 million in ETH from more than 11,000 investors, becoming the largest crowdfunding project at the time. However, a flaw in its smart contract—a reentrancy vulnerability—was exploited in June 2016, resulting in the theft of 3.6 million ETH.
Attackers funneled funds into a child DAO, where they remained locked for 28 days due to withdrawal restrictions.
To recover stolen funds, the community voted on EIP-779, proposing a hard fork to reverse the transaction history. While most miners supported it, a portion of the community opposed intervention on philosophical grounds—believing blockchain immutability should not be compromised.
This disagreement led to a permanent split:
- The new chain retained the name Ethereum (ETH)
- The original chain continued as Ethereum Classic (ETC)
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Metropolis: Preparing for Proof of Stake
The Metropolis phase was designed to lay the groundwork for Ethereum’s shift from Proof of Work (PoW) to Proof of Stake (PoS). It consisted of two major hard forks:
Byzantium (October 2017)
This upgrade reduced block rewards from 5 ETH to 3 ETH, discouraging excessive mining and signaling the network’s gradual move away from PoW. It also improved privacy and smart contract efficiency through various EIPs.
Constantinople and Istanbul
Deployed in two parts—Petersburg and Istanbul—this fork further reduced miner rewards to 2 ETH per block via EIP-1234.
The Istanbul update, launched on December 8, 2019, optimized gas costs and enabled advanced Layer 2 scaling technologies such as zero-knowledge rollups (zk-SNARKs/STARKs)—critical for future scalability.
Beacon Chain: Introducing Proof of Stake
Launched in December 2020, the Beacon Chain was Ethereum’s dedicated PoS coordination layer. Running parallel to the original PoW chain, it managed validator assignments, staking mechanics, and consensus without processing user transactions initially.
Key features included:
- Minimum stake requirement: 32 ETH
- Validator rewards for securing the network
- Preparation for full integration via “The Merge”
However, stakers could not withdraw their ETH or claim rewards until further upgrades enabled these functions.
The Merge: Transition to Proof of Stake
On September 15, 2022, Ethereum completed The Merge, fully integrating the Beacon Chain with the mainnet. This landmark event:
- Permanently replaced PoW with PoS
- Reduced energy consumption by ~99.95%
- Lowered barriers to node operation, enhancing decentralization
- Improved transaction finality and network security
The Merge marked Ethereum’s transformation into a sustainable and secure blockchain platform.
Shanghai Upgrade (Shapella): Unlocking Staking Withdrawals
On April 14, 2023, the Shanghai (execution layer) and Capella (consensus layer) upgrades—collectively known as Shapella—were deployed. For the first time, validators could:
- Withdraw their staked ETH
- Claim accumulated staking rewards
- Add withdrawal credentials post-deposit
Within 24 hours, around 180,000 ETH were withdrawn—95% being accrued rewards—demonstrating strong demand for liquidity.
This upgrade completed Ethereum’s transition to a fully functional PoS system.
Frequently Asked Questions
Q: What is a hard fork in Ethereum?
A: A hard fork is a permanent protocol upgrade that makes previous versions invalid. All nodes must update to remain on the network.
Q: Why did Ethereum split into Ethereum and Ethereum Classic?
A: After The DAO hack, a hard fork recovered stolen funds. Those who opposed changing transaction history continued on the original chain—now Ethereum Classic.
Q: What was the purpose of The Merge?
A: The Merge transitioned Ethereum from energy-intensive Proof of Work to efficient Proof of Stake, drastically cutting power use and improving scalability.
Q: Can I now withdraw staked Ethereum?
A: Yes—since the Shapella upgrade in April 2023, validators can withdraw both staked ETH and earned rewards.
Q: How many EIPs are typically included in a hard fork?
A: A hard fork can include multiple EIPs. For example, Byzantium implemented eight key proposals to enhance security and efficiency.
Q: What comes after Shapella?
A: The focus now shifts to scaling solutions like sharding, aiming to increase throughput from ~29 TPS to up to 10,000 TPS.
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Final Thoughts
With Ethereum now fully operating under Proof of Stake, developers can focus on solving its biggest remaining challenge: scalability. Future upgrades like sharding promise massive improvements in transaction speed and cost-efficiency.
Meanwhile, liquid staking platforms are gaining traction thanks to withdrawal capabilities enabled by Shapella. As Ethereum continues its evolution, each hard fork remains a testament to its resilience, adaptability, and community-driven innovation.