Ethereum Classic ETC

Ethereum Classic is the original Ethereum blockchain, continuing unaltered. In 2016 an investment fund built on Ethereum called The DAO was drained of roughly a third of its funds through a flaw in its code. The community voted to change the ledger to reverse it; the chain that adopted that change is the Ethereum most people use today, and the chain that refused it is Ethereum Classic.

The disagreement was about a principle rather than a feature. If a ledger can be rewritten when the outcome is bad enough, the argument runs, then immutability is a convention rather than a guarantee — so ETC kept the record as it was written, including the theft. It also kept proof-of-work mining after Ethereum moved to proof of stake in 2022.

That principled position has a measurable cost. A smaller chain sharing a mining algorithm with much larger ones can be attacked by temporarily renting more computing power than it has, and Ethereum Classic has suffered several such reorganisations, including a run of them in 2020. Development activity and application usage are a small fraction of Ethereum's. It is not a cheaper version of Ethereum — it is a separate network that does not share its ecosystem.