Ethereum Classic
The largest proof-of-work smart contract platform preserving Ethereum's original history.
Ethereum Classic is a blockchain-based distributed computing platform offering smart contract functionality. It was created in a hard fork from the mainline Ethereum blockchain, maintaining the original, unaltered ledger prior to the attempt to reverse a hacking attack on The DAO in July 2016. Following Ethereum's transition to proof-of-stake in 2022, it is now the largest smart contract platform secured by a proof-of-work consensus mechanism. It is open source and supports a modified version of Nakamoto consensus via transaction-based state transitions executed on a public Ethereum Virtual Machine (EVM). The network uses the native Ether token (ETC), created as a reward to nodes for mining, which validates computations on the EVM.
- Network Type
- Proof-of-Work Blockchain
- Original Fork Date
- July 2016
- Primary Use Case
- Smart Contracts
Verified Timeline
Lore & Background
On July 30, 2015, the Ethereum mainnet launched via Frontier. By June 9, 2016, a critical recursive call vulnerability in The DAO project was publicly disclosed, leading to the theft of $50 million worth of Ether on June 17. On July 20, 2016, the Ethereum Foundation implemented an irregular state change to erase this theft from the blockchain history, creating a new chain branded as Ethereum (ETH). A significant portion of the community refused this alteration, continuing to run the original, unaltered version which was renamed Ethereum Classic (ETC). This split resulted in two distinct networks: one with altered history and one preserving the original ledger. Since then, ETC has maintained its commitment to immutability, refusing future transitions to proof-of-stake.
In Their Own Story
The narrative of Ethereum Classic is defined by a single moment on July 20, 2016, when the network split. While the majority voted to reverse a hack through an irregular state change, a minority held firm to the principle that the ledger must remain unaltered. These participants continued mining block 1,920,000, the first block exclusive to the new chain. Over the years, this commitment led to specific technical evolutions, such as defusing the 'Difficulty Bomb' at block 5,900,000 to stay on proof-of-work and adopting the ETChash algorithm in 2020 to secure against 51% attacks. Today, the chain stands as a direct continuation of the original Ethereum codebase from 2015.
Reader's Guide
Ethereum Classic (ETC) operates using accounts and balances rather than unspent transaction outputs (UTXOs). Transactions are validated by miners solving cryptographic puzzles under the ETChash algorithm, which doubled the Ethash epoch duration to 60,000 blocks. Users interact via addresses starting with '0x' followed by 40 hexadecimal digits, derived from the Keccak-256 hash of a public key. The native token, ETC, is used to pay for Gas, the unit of computation required for transactions and state transitions on the network.
Did You Know?
- The first Ethereum Classic block not included in the forked Ethereum chain was number 1,920,000.
- Ethereum Classic permanently defused the 'Difficulty Bomb' at block 5,900,000 to commit exclusively to proof-of-work.
- In 2020, ETC modified its mining algorithm to ETChash by doubling the epoch duration from 30,000 to 60,000 blocks.
- Ethereum Classic achieved full protocol parity with Ethereum through the Phoenix upgrade in January 2020.
- By 2025, the network's hashrate surpassed 300 terahashes per second (TH/s).
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