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The Ethereum Classic logo
|Initial release||30 July 2015|
|Written in||C++, Go, Rust, Scala|
|Operating system||Clients available for Linux, Windows, macOS, POSIX|
|License||Multiple open-source licenses|
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 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 in 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.
In May 2016, a venture capital fund called The DAO built on Ethereum raised around $168 million, with the intention of investing in projects using smart contracts. In the same month a paper was released detailing security vulnerabilities with The DAO that could allow ether to be stolen. In June, 3.6 million Ether (approximately $50 million USD) was taken from accounts in The DAO and moved to another account without the owners' consent, exploiting one of the vulnerabilities that had been raised in May. Members of The DAO and the Ethereum community debated what actions, if any, should occur to resolve the situation. A vote occurred and in July 2016 it was decided to implement a hard fork in the Ethereum code and to move the Ether taken in the exploit to a new smart contract through which it would be restored to the owners from whom it had been taken.
Ethereum Classic came into existence when some members of the Ethereum community rejected the hard fork on the grounds of "immutability", the principle that the blockchain cannot be changed, and decided to keep using the unforked version of Ethereum.
Ethereum Classic underwent a technical hard fork to adjust the internal pricing for running various op codes on the Ethereum Virtual Machine (EVM) on 25 October 2016, similar to the hard fork the ETH chain did a week earlier. The goal was to more rationally price various compute-intensive and external reference commands to reduce the incentive for spammers who had conducted a month-long distributed denial-of-service attack on the Ethereum Classic network. A hard fork that occurred early 2017 successfully delayed the so-called "difficulty bomb", originally added to Ethereum's code in September 2015 in order to exponentially increase the difficulty of mining, or the competitive process by which new transaction blocks are added to the network. The people who continued with Ethereum Classic advocate for blockchain immutability, and the concept that "code is law"  against the pro-fork side (Ethereum) which largely argued for extra-protocol intentionality, decentralized decision-making, and conflict resolution. Various critics of Ethereum Classic have denounced it as a scam and a potential theft of intellectual property, with similar controversial remarks being made on behalf of the opposing camp. Ethereum Classic has retained some users of Ethereum and has also attracted others from the wider crypto-community who reject contentious forks on ideological grounds. The project, however, is not officially supported by the Ethereum Foundation.
On June 29, 2017 the Ethereum Classic Twitter account made a public statement indicating reason to believe that the Classic Ether Wallet Website had been compromised.  Information security news organization Threatpost later reported that the compromise occurred due to a social engineering attack against the CEW websites domain registrar 1&1. The Ethereum Classic Twitter account confirmed the details released via Threatpost.  The Ethereum Classic team worked with CloudFlare, a company specializing in internet security services, to place a warning on the compromised domain warning users of the phishing attack.  The ClassicEtherWallet.com domain is now only a redirect to the Github Page Site of the wallet.
|Release Date||Code name||Milestones & Hard Forks|
|July 30, 2015||Frontier||The release of the Ethereum Genesis block.|
|March 14, 2016||Homestead||The 2nd major release of the Ethereum platform, which introduced EIP-2, EIP-7, and EIP-8.|
|October 25, 2016||GasReprice||First fork after being renamed "Ethereum Classic". Repriced some operations to prevent DoS attacks affecting both Ethereum and Ethereum Classic networks. Introduced ECIP-1050.|
|January 14, 2017||Die Hard||Delayed the difficulty bomb which was originally intended to force the network to move from proof-of-work to proof-of-stake and added replay protection to prevent transactions on the Ethereum network being accepted on the Ethereum Classic chain. Introduced ECIP-1010 and EIP-155.|
|December 11, 2017||Monetary policy change||Change unlimited token emission to a fixed-cap monetary policy similar to bitcoin with a hard cap of around 210 Million.|