Ethereum Classic (opens in a new tab) (ETC) is the Ethereum blockchain that never rewrote its own history. Its ledger runs back to 30 July 2015, when Ethereum launched, and it simply leaves out the intervention of July 2016 that produced the Ethereum most people know today. That intervention followed the draining of The DAO, a crowdfunded smart contract that an attacker emptied of more than 3.6 million ether by exploiting a flaw in its code. A hard fork at block 1,920,000 moved the funds to a contract where DAO investors could reclaim them. Some miners refused to follow, arguing that the protocol had done exactly what it was told, and the unaltered chain they kept running started trading as ETC within days.
Behind that refusal is the principle of "code is law". Whatever a smart contract does is final, even when a bug causes it, and the project's website rules out do-overs, bailouts or refunds unless a contract was written to allow them. Nobody is formally in charge either: in the website's own words, there is "no official anything" in Ethereum Classic. Changes to the protocol are argued out in public proposals called ECIPs.
Mining still secures the network. When Ethereum moved to proof of stake with The Merge on 15 September 2022, ETC kept proof of work and took in many of the miners Ethereum no longer needed; the project now calls it the largest proof-of-work network for smart contracts. Its mining algorithm, Etchash, is a modified form of Ethash introduced with the Thanos upgrade (ECIP-1099) in November 2020, which recalibrated the way the DAG, a large dataset used in mining, is calculated.
The early years were harder on security. While Ethereum's mining power still dwarfed its own, attackers gained majority control of ETC in January 2019 and on three occasions in the summer of 2020, rewriting recent blocks to spend the same coins twice at exchanges. Exchanges responded by waiting for more confirmations, and in October 2020 the Core-Geth node software added MESS, a rule that makes nodes resist unusually deep reorganisations. With far more hashrate on the chain after The Merge, MESS was switched off by default at the Spiral upgrade in February 2024.
Issuance follows ECIP-1017, nicknamed 5M20. Every five million blocks the reward falls by a fifth, and the sixth era, which began with block 25,000,001 on 22 July 2026, pays 1.6384 ETC per block. When you withdraw, pick the Ethereum Classic network rather than Ethereum; the Ethereum Classic network page lists the platforms that support it. ETC is priced separately from ether, and a sharp fall in its euro value can happen within days.
Official website: ethereumclassic.org (opens in a new tab)