What consensus mechanism did Ethereum adopt after The Merge in September 2022?

Ethereum adopted proof of stake after The Merge in September 2022.

The Merge was Ethereum’s transition from its original proof-of-work consensus system to proof of stake. It connected Ethereum’s execution layer, which processes transactions and smart contracts, with the Beacon Chain, Ethereum’s proof-of-stake coordination layer. The change was completed on 15 September 2022.

Under proof of stake, validators propose and attest to blocks after depositing Ether as collateral. This replaced Ethereum’s former mining-based system, in which computers competed to solve computational puzzles. Validators can lose part of their deposit through penalties for certain dishonest or seriously faulty behavior.

The Merge did not create a new cryptocurrency, erase Ethereum’s transaction history, or immediately make transactions free. It changed how the network reaches agreement and greatly reduced the energy required for block production. Later upgrades, including Shanghai in 2023, addressed additional network features such as withdrawals of staked Ether.