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Page last updated: May 16, 2022

The history of Ethereum

A timeline of all the major milestones, forks, and updates to the Ethereum blockchain.

Looking for future protocol upgrades? Learn about upcoming upgrades to Ethereum.

2021

Arrow Glacier

Summary

The Arrow Glacier network upgrade pushed back the difficulty bomb by several months. This is the only change introduced in this upgrade, and is similar in nature to the Muir Glacier upgrade. Similar changes have been performed on the Byzantium, Constantinople and London network upgrades.

• EF Blog - Arrow Glacier Upgrade Announcement
• Ethereum Cat Herders - Ethereum Arrow Glacier Upgrade

Node operators

Be sure to upgrade your client software to the latest version before December 5, 2021 to account for variable block times. This will help avoid having your client sync to a pre-fork chain, resulting in the inability to send funds or properly verify transactions.

Altair

Summary

The Altair upgrade was the first scheduled upgrade for the Beacon Chain. It added support for "sync committees"—enabling light clients, and bringing validator inactivity and slashing penalties up to their full values.

• Read the Altair upgrade specification

Fun fact!

Altair was the first major network upgrade that had an exact rollout time. Every upgrade prior had been based on a declared block number on the proof-of-work chain, where block times vary. The Beacon Chain does not require solving for proof-of-work, and instead works on a time-based epoch system consisting of 32 twelve-second "slots" of time where validators can propose blocks. This is why we knew exactly when we would hit epoch 74,240 and Altair became live!

• Beaconcha.in Glossary - Slots

London

Summary

The London upgrade introduced EIP-1559, which reformed the transaction fee market, along with changes to how gas refunds are handled and the Ice Age schedule.

• Are you a dApp developer? Be sure to upgrade your libraries and tooling.
• Read the Ethereum Foundation announcement
• Read the Ethereum Cat Herder's explainer

Berlin

Summary

The Berlin upgrade optimized gas cost for certain EVM actions, and increases support for multiple transaction types.

• Read the Ethereum Foundation announcement
• Read the Ethereum Cat Herder's explainer

2020

Beacon Chain genesis

Summary

The Beacon Chain needed 16384 deposits of 32 staked ETH to ship securely. This happened on November 27, meaning the Beacon Chain started producing blocks on December 1, 2020. This is an important first step in achieving the Ethereum vision.

Read the Ethereum Foundation announcement

The Beacon Chain

Staking deposit contract deployed

Summary

The staking deposit contract introduced staking to the Ethereum ecosystem. Although a Mainnet contract, it had a direct impact on the timeline for launching the Beacon Chain, an important Ethereum upgrade.

Read the Ethereum Foundation announcement

Staking

Muir Glacier

Summary

The Muir Glacier fork introduced a delay to the difficulty bomb. Increases in block difficulty of the proof-of-work consensus mechanism threatened to degrade the usability of Ethereum by increasing wait times for sending transactions and using dapps.

• Read the Ethereum Foundation announcement
• Read the Ethereum Cat Herder's explainer

2019

Istanbul

Summary

The Istanbul fork:

• Optimised the gas cost of certain actions in the EVM.
• Improved denial-of-service attack resilience.
• Made Layer 2 scaling solutions based on SNARKs and STARKs more performant.
• Enabled Ethereum and Zcash to interoperate.
• Allowed contracts to introduce more creative functions.

Read the Ethereum Foundation announcement

Constantinople

Summary

The Constantinople fork:

• Ensured the blockchain didn't freeze before proof-of-stake was implemented.
• Optimised the gas cost of certain actions in the EVM.
• Added the ability to interact with addresses that haven't been created yet.

Read the Ethereum Foundation announcement

2017

Byzantium

Summary

The Byzantium fork:

• Reduced block mining rewards from 5 to 3 ETH.
• Delayed the difficulty bomb by a year.
• Added ability to make non-state-changing calls to other contracts.
• Added certain cryptography methods to allow for layer 2 scaling.

Read the Ethereum Foundation announcement

2016

Spurious Dragon

Summary

The Spurious Dragon fork was the second response to the denial of service (DoS) attacks on the network (September/October 2016) including:

• tuning opcode pricing to prevent future attacks on the network.
• enabling “debloat” of the blockchain state.
• adding replay attack protection.

Read the Ethereum Foundation announcement

Tangerine whistle

Summary

The Tangerine Whistle fork was the first response to the denial of service (DoS) attacks on the network (September/October 2016) including:

• addressing urgent network health issues concerning underpriced operation codes.

Read the Ethereum Foundation announcement

DAO fork

Summary

The DAO fork was in response to the 2016 DAO attack where an insecure DAO contract was drained of over 3.6 million ETH in a hack. The fork moved the funds from the faulty contract to a new contract with a single function: withdraw. Anyone who lost funds could withdraw 1 ETH for every 100 DAO tokens in their wallets.

This course of action was voted on by the Ethereum community. Any ETH holder was able to vote via a transaction on a voting platform. The decision to fork reached over 85% of the votes.

Some miners refused to fork because the DAO incident wasn't a defect in the protocol. They went on to form Ethereum Classic.

Read the Ethereum Foundation announcement

Homestead

Summary

The Homestead fork that looked to the future. It included several protocol changes and a networking change that gave Ethereum the ability to do further network upgrades.

Read the Ethereum Foundation announcement

2015

Frontier thawing

Summary

The frontier thawing fork lifted the 5,000 gas limit per block and set the default gas price to 51 gwei. This allowed for transactions – transactions require 21,000 gas.

Read the Ethereum Foundation announcement

Frontier

Summary

Frontier was a live, but barebone implementation of the Ethereum project. It followed the successful Olympic testing phase. It was intended for technical users, specifically developers. Blocks had a gas limit of 5,000. This ‘thawing’ period enabled miners to start their operations and for early adopters to install their clients without having to ‘rush’.

Read the Ethereum Foundation announcement

2014

Ether sale

Ether officially went on sale for 42 days. You could buy it with BTC.

Read the Ethereum Foundation announcement

Yellowpaper released

The Yellow Paper, authored by Dr. Gavin Wood, is a technical definition of the Ethereum protocol.

View the Yellow Paper

2013

Whitepaper released

The introductory paper, published in 2013 by Vitalik Buterin, the founder of Ethereum, before the project's launch in 2015.

Whitepaper