Ethereum Classic (ETC) was created via hard fork in July 2016 after the DAO hack, when a part of the Ethereum community believed that blockchain transactions should be immutable out of principle.
However, others wanted to roll back Ethereum blockchain to make sure that malicious transactions would not be included. Those who were opposed to the roll back decided to stick with the original chain, and called it “Ethereum Classic”. According to the hard fork definition, Ethereum Classic is thus the opposite of Bitcoin Cash (BCH), which launched as a new chain and the original Bitcoin continued on the old one.
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https://coinidol.com/ethereum-classic-follow-success-of-bitcoin-cash/