https://techcrunch.com/2022/09/15/ethereum-switches-to-proof-of-stake-consensus-after-completing-the-merge/

Popular cryptocurrency blockchain Ethereum has completed its long-awaited switch to proof-of-stake. That upgrade process, better known as ‘The Merge’, has been years in the making. According to the Ethereum Foundation, today’s transition reduces Ethereum’s energy consumption by 99.95%.

Previously, the Ethereum blockchain relied on proof-of-work, a consensus mechanism that requires a lot of computational effort from all the decentralized nodes participating in the blockchain.