Ethereum Classic is an open-source, public, blockchain-based distributed computing platform featuring smart contract (scripting) functionality. It provides a decentralized Turing-complete virtual machine, the Ethereum Virtual Machine (EVM), which can execute scripts using an international network of public nodes. Ethereum Classic also provides a value token called "classic ether", which can be transferred between participants, stored in a cryptocurrency wallet and is used to compensate participant nodes for computations performed. The classic ether token is traded on cryptocurrency exchanges under the ticker symbol ETC. Gas, an internal transaction pricing mechanism, is used to prevent spam on the network and allocate resources proportionally to the incentive offered by the request.

The Ethereum platform has been forked into two versions: "Ethereum Classic" (ETC) and "Ethereum" (ETH). Prior to the fork, the token had been called Ethereum. After the fork, the new tokens kept the name Ethereum (ETH), and the old tokens were renamed Ethereum Classic (ETC). Ethereum Classic appeared as a result of a disagreement with the Ethereum Foundation regarding The DAO Hard Fork. It united members of the Ethereum community who rejected the hard fork on philosophical grounds. Users that owned ETH before the DAO hard fork (block 1920000) own an equal amount of ETC after the fork.

Ethereum Classic passed a technical hard fork to adjust the internal prices for various opcodes of the Ethereum Virtual Machine (EVM) on October 25, 2016, similar to the hard fork committed by Ethereum a week previously. The purpose of the hard fork was a more rational distribution of payments for resource-intensive calculations, which led to the elimination of the favorable conditions for attacks that were previously conducted on ETH and ETC. A hard fork held at the beginning of 2017 successfully delayed the "bomb complexity" that was added to the Ethereum code in September 2015 with a view of exponentially increasing the complexity of mining and the process of calculation of new network units. In late 2017, a hard fork occurred which changed the monetary policy with unlimited emissions to a system similar to Bitcoin.