The Merge
The September 2022 Ethereum upgrade that replaced its original proof-of-work consensus mechanism with proof-of-stake, without changing the network's execution layer or user-facing activity.
The Merge was the Ethereum network upgrade, completed in September 2022, that replaced Ethereum's original proof-of-work (see Kaavon's "Proof of Work" glossary definition) consensus mechanism with proof-of-stake (see Kaavon's "Proof of Stake" glossary definition), by merging the existing execution layer, which handled transactions and smart contracts, with a separate proof-of-stake consensus layer, called the Beacon Chain, that had been running in parallel since late 2020 specifically to prepare for this transition.
Because The Merge changed only how new blocks reached consensus — not Ethereum's execution environment, account balances, smart contract code, or application-layer user experience — the transition was designed to be effectively invisible to ordinary users and applications, with transaction history, balances, and smart contracts all carrying over unchanged. The upgrade's most significant practical effects were eliminating energy-intensive mining in favor of staking, and reducing Ethereum's new ETH issuance rate substantially compared to its proof-of-work emission schedule.
Examples
- The Merge changed only Ethereum's underlying consensus mechanism, leaving account balances, smart contracts, and application behavior completely unaffected.
- After The Merge, Ethereum's new ETH issuance rate dropped substantially compared to its prior proof-of-work emission schedule, since validators require far less new issuance to be incentivized than miners did.